help gmod pink and black checker whole screen

[gizmod]

When my son tries to play gmode the whole screen is black and pink checkers but you can still hear yourself shooting your gun. You cant see anything! What do I do? I never play gmod so please give me the dummy version . lol Thanks!
Shayne

[Rubat]

Here are your options:
1) In game, press Q and click Post Processing tab. Uncheck every checkbox you can find there, in every category on the left.
2) Unmount Portal 2 and L4D2 ( Main menu > Controller icon in bottom right corner > Uncheck checkboxes near said titles )
3) Verify integrity of game cache ( In Steam, right click on GMod > Properties > Local Files tab )

[Coldud13]

Or you can mount games that Garry's mod is heavily relied on such as counter strike source and the half life 2 episodes.

[c👌de_g🎷]

[QUOTE=coldud13;44645836]Or you can mount games that Garry's mod is heavily relied on such as counter strike source and the half life 2 episodes.[/QUOTE]

Not those kind of missing textures.