I have this problem where once i open radiant, everything is fine and all the textures show. But when open a blank map all the textures suddenly disappear. If anyone knows how to fix this please help.

You need to browse the textures by either their surface type or usage. Radiant shows them on an existing map because the map uses them.

https://www.mediafire.com/download/9x42e4z4yyis2px

Load prefab into your map to get all textures. Delete prefab before compiling or launcher will give errors.