map is black when i start

alright, its been like this for a month. i’ve uninstalled addons. i’ve deleted my local content (uninstalled) and reinstalled. i dont know what to do. it started when i was dicking around with post processes. i turned on what i believe to be stereo stopicsy and frame blending, i think, i know it was something in post process i was messing with. got hit by a antlion guard, the screen glitched, then black. i mean total black, everything was going on, i got killed by the antlion, and could spawn things. but couldn’t see the hud, spawn menu, or pause menu. i could find the quit button, then quit, then i can see the main menu. i try another map, it starts as black, above conditions apply. i really want to play garrys mod, plz help me.