Ok, Here is the problem I Bought and downloaded COD WAW a few days ago with the Sole Purpose to Play Modded zombies.
I downloaded UGX Map Manager Because it seemed like it would be simple and it would keep me from getting Headaches like the one i have now over this.
So i Started up UGXMM and downloaded one of the maps that looked pretty Cool (Leviathan 1.2)
I launched the map from UGXMM And went to the mods tab to launch the map.
Only Problem is that there isnt anything on the mods list... It says Not Only "Launch" But also "Launch W/o Mods" Bringing me to believe that the game beleives there is a mod installed.
I checked my mods folder under Appdata/local/Activison/CoDWAW/Players/profiles/(My IGN)/Mods
The only thing in the Mods folder are the Articles mpdata and mpdatabk0000
Please help me fast... im seriously about to Slap a Deaf Juvenile

They go in C:\Users\<NAME>\AppData\Local\Activision\CoDWaW\mods
Mods are downloaded and put in there.

If you're launching WaW from somewhere don't. Only launch through Steam or manual.

You may also need to run Map Manager as admin, even if your PC user has admin privileges. Right click -> Run as Administrator.

he downloaded cod waw for the sole purpose of playing Leviathan thak you for the compliment

So running UGXMM as an admin should fix it. correct?

Ok i Just felt Euphoria... The mods were Downloading to the incorrect place,(Thanks DidUknowipwn ) so i rectified that.
Now i can see the maps in the Mods tab on COD WAW. Only Problem is i select the map and click launch and it just restarts COD WAW and brings me back to the menu...
THIS PROBLEM SHALL BE FIXED

Ok i Just felt Euphoria... The mods were Downloading to the incorrect place,(Thanks DidUknowipwn ) so i rectified that.
Now i can see the maps in the Mods tab on COD WAW. Only Problem is i select the map and click launch and it just restarts COD WAW and brings me back to the menu...
THIS PROBLEM SHALL BE FIXED

Depending on what mod you downloaded, some maps just use the same menu as the default menu. The mod probably did load, the menu just appears the same as the default waw menu. Most maps nowadays use custom menus but some dont. So if this is the case, launch the mod, click the ~ key to open the console, and type "map MAPNAME" and of course replace mapname with the name of the map you are launching.

So if i want to launch SuperMario64 i would do map supermario64
Or map Levithan1.2?

So if i want to launch SuperMario64 i would do map supermario64
Or map Levithan1.2?

If I'm not mistaken, both maps you've mentioned have a main menu button for Solo, Leviathan definitely does.