Default is always 0

i managed to get a bank working with this, weapon locker though is still nonworking. i'll keep trying though

weapon = player GetCurrentWeapon();
keys = GetArrayKeys( level.zombie_weapons );
for( i = 0; i < keys.size; i ++ )
{
	if( keys[i] == weapon )
	{
		player SetStat( 3005, i );
		break;
	}
}

keys = GetArrayKeys( level.zombie_weapons );
weapon = keys[ player GetStat( 3005 ) ];

this might be because you followed what Ray1235 told you to do, which was use level.zombie_weapons. level.zombie_weapons is not an array of integers, remember the array keys are all of the weapon names. That means if u use an integer to get something in that array like he told you to do, it will come up undefined. My best recommendation would be to list out all the weapons in an array of integers separately and use that. But if you want something easier,  this *MIGHT work.

weapon = player GetCurrentWeapon();
keys = GetArrayKeys( level.zombie_weapons );
for( i = 0; i < keys.size; i ++ )
{
	if( keys[i] == weapon )
	{
		player SetStat( 3005, i );
		break;
	}
}

keys = GetArrayKeys( level.zombie_weapons );
weapon = keys[ player GetStat( 3005 ) ];

level.zombie_weapons is an array of structs, so you can't just compare

level.zombie_weapons[i]

with a weapon name
You have to do

level.zombie_weapons[i].weapon_name == <weapon name>

keys = GetArrayKeys( level.zombie_weapons );
keys[i] == weapon

i got it to work using alaurenc9's method, im just gonna do a few tests, then i'll update the script

I think if we start making things with setStat, we all should save the number of the stat in a global variable, like:

level.stats[ "weapon_storage_locker" ] = 3005;

So we can easily change them to avoid overwriting other things. Because if I wanted to add this and the bank to my map, I would have to find every line where setStat or getStat is written to change the number, but maybe someone with no idea in scripting wouldn't know that.
Just my opinion.

I think if we start making things with setStat, we all should save the number of the stat in a global variable, like:

level.stats[ "weapon_storage_locker" ] = 3005;

So we can easily change them to avoid overwriting other things. Because if I wanted to add this and the bank to my map, I would have to find every line where setStat or getStat is written to change the number, but maybe someone with no idea in scripting wouldn't know that.
Just my opinion.

dont worry, the bank uses 3005 and this uses 3006-3009. it should only need to be changed if your using one of those for something else

I'm confused....

You defined literally every variable on the user. Only the stored information needs to be defined on the user. Everything else are just temporary variables that do not need to be this way. Here is how I would put the script together.

weapon_locker_begin()
{
	players = GetPlayers();
	for( i = 0; i < players.size; i ++ )
	{
		players[i] thread get_stored_gun();
	}
	level thread weapon_locker();
}

get_stored_gun()
{
	wait 1;
	keys = GetArrayKeys( level.zombie_weapons );
	self.stored_weapon = keys[ self GetStat( 3006 ) ];
	self.stored_ammo_clip = self GetStat( 3007 );
	self.stored_ammo_stock = self GetStat( 3008 );
	self.has_stored_weapon = self GetStat( 3009 );
}

weapon_locker()
{
	wait 2;
	weapon_locker = GetEnt( "weapon_locker", "targetname" );
	weapon_locker SetHintString( "Press & hold &&1 to Store Current Weapon" );
	weapon_locker SetCursorHint( "HINT_NOICON" );
	while( true )
	{
		weapon_locker waittill( "trigger", user );
		if( is_player_valid( user ) )
		{	
			weapon = user GetCurrentWeapon();
			gun_ammo_clip = user GetWeaponAmmoClip( weapon );
			gun_ammo_stock = user GetWeaponAmmoStock( weapon );
			if( weapon == "colt" || weapon == "zombie_colt" || weapon == "zombie_colt_upgraded" || weapon == "tesla_gun" || weapon == "tesla_gun_upgraded" || weapon == "thundergun" || weapon == "thundergun_upgraded" || weapon == "ray_gun" || weapon == "ray_gun_upgraded" || weapon == "scavenger" || weapon == "scavenger_upgraded" || weapon == "vorkuta_knife" || weapon == "vorkuta_knife_upgraded" ) 	
			{	
				user IPrintLnBold( "^7You Cannot Store This Weapon" );
				wait 2;
			}
			else if( weapon == "none" || weapon == "syrette" || weapon == "zombie_melee" || weapon == "zombie_perk_bottle_revive" || weapon == "zombie_perk_bottle_doubletap" || weapon == "zombie_perk_bottle_jugg" || weapon == "zombie_perk_bottle_sleight" || weapon == "zombie_perk_bottle_staminup" || weapon == "zombie_perk_bottle_phd" || weapon == "zombie_perk_bottle_mulekick" || weapon == "zombie_perk_bottle_deadshot" || weapon == "zombie_perk_bottle_cherry" || weapon == "zombie_perk_bottle_vulture" || weapon == "zombie_knuckle_crack" || weapon == "stielhandgranate" || weapon == "zombie_cymbal_monkey" || weapon == "zombie_bowie_flourish" )
			{
				user IPrintLnBold( "^7You Are Not Holding a Weapon" );
				wait 2;
			}
			else
			{
				PrimaryWeapons = user GetWeaponsListPrimaries();
				weapon_limit = 2;
				if( user HasPerk( "specialty_extraammo" ) )
				{
					weapon_limit = 3;
				}
				if( IsDefined( PrimaryWeapons ) && PrimaryWeapons.size < weapon_limit && user.has_stored_weapon == 1 )
				{
					user GiveWeapon( user.stored_weapon );
					user SetWeaponAmmoClip( user.stored_weapon, user.stored_ammo_clip );
					user SetWeaponAmmoStock( user.stored_weapon, user.stored_ammo_stock );
					user SwitchToWeapon( user.stored_weapon );
					user.stored_weapon = "";
					user.stored_ammo_clip = 0;
					user.stored_ammo_stock = 0;
					user.has_stored_weapon = 0;
				}
				else
				{
					user TakeWeapon( weapon );
	   				if( user.has_stored_weapon == 1 )
					{
						user GiveWeapon( user.stored_weapon );
						user SetWeaponAmmoClip( user.stored_weapon, user.stored_ammo_clip );
						user SetWeaponAmmoStock( user.stored_weapon, user.stored_ammo_stock );
						user SwitchToWeapon( user.stored_weapon );
					}
					else if( IsDefined( PrimaryWeapons ) && PrimaryWeapons.size > 0 )
					{
						user SwitchToWeapon( PrimaryWeapons[0] );
					}
					user.stored_weapon = weapon;
					user.stored_ammo_clip = gun_ammo_clip;
					user.stored_ammo_stock = gun_ammo_stock;
					user.has_stored_weapon = 1;
				}
				index = 0;
				keys = GetArrayKeys( level.zombie_weapons );
				for( i = 0; i < keys.size; i ++ )
				{
					if( keys[i] == user.stored_weapon )
					{
						index = i;
						break;
					}
				}
				user SetStat( 3006, index );
				user SetStat( 3007, user.stored_ammo_clip );
				user SetStat( 3008, user.stored_ammo_stock );
				user SetStat( 3009, user.has_stored_weapon );
				user PlayLocalSound( "cha_ching" );
				wait 2;
			}
		}
	}
}

I also made it where if you are under the weapon limit, and you have a stored weapon, you can simply take it out without trading your current weapon and have no stored weapon in the locker. Otherwise it will store your current weapon, and if you had a stored weapon, it will give you it. Of course if you feel that it is now more of my script than your script, you don't have to use it. But I don't mind you taking this script and calling it yours and using it etc. as long as credit is given.

i used varriables cause i was just adapting my original script, its also a little chuncky, i'll probably make a better one later, and i didnt make it ake the weapon if you have a free slot since the bo2 one didnt (at least i dont think it did)

According to the bo2 script, yes you can take the weapon if you have a free slot and it clears the weapon locker data. So my script is accurate completely to bo2. Anyways let me know if you are going to use my script. If you aren't could you at least do me a favor and test it for me? Because if you don't use it, I want to release it in my own post, and I'll credit you for original script. Would you mind if I did that?