Major graphics problems

After reinstalling gmod not long ago, my game seems to have major graphics problems to the point where it may be almost unplayable in multiplayer
I have rendering problems, where objects either go black or all sorts of colours (http://steamcommunity.com/sharedfiles/filedetails/?id=157533060) metropolice and some other addon npc’s seem to have this strange pose when attacking (http://steamcommunity.com/profiles/76561198045204504/screenshots/), gm_construct (as well as various other maps) are missing almost all the textures, custom playermodels end up in the t-pose and vanilla garrysmod playermodels either appear as the ERROR prop or dont appear at all, however the npcs that use their models seem perfectly normal

if there is anyway I can fix this without reinstalling (because my download speed is at a baffling 50kb/s), can you please tell me?, Ill try to get more screenshots if required

opt in to steampipe beta on all the source games u own and play them at least once. Then mount them in Garrysmod. If that doesn’t fix it completely delete and reinstall Gmod. That will almost always fix it.