If you are here you are more than likely looking for a way to fix your Counter-Strike:Source texture and model related errors. If so then you are in the right place! Before you start please proceed to open this website in your desktop browser after closing Garry's Mod as this fix requires you to restart your Garry's Mod anyways.

Before proceeding please download the following list below:
Winrar: Winrar Download Directory (Pick the version corresponding to your operating system)
CS:S Textures Download: CS:S Textures

First: Make sure that you have downloaded and installed WinRAR so that you can extract the contents of the zip folder.

Second: Download the CS:S Textures and go to the downloaded compressed file which should be called CSSGameContent. Next right click the folder, and select "Extract to CSSGameContent /", doing this will create a seperate folder.

Third: Now go to your Steam Library. Right Click "Garry's Mod" and go to Properties --> Local Files --> Browse Local Files. Enter the "garrysmod" folder, than open the "addons" Folder.

Fourth: Open the contents of the decompiled folder called CSSGameContent that you previously extracted, you should see a folder called CSS_Game_Content.

Fifth: Now just drag the entire folder called CSS_Game_Content into your addons folder and you will be all set AFTER you close and reopen your Garry's Mod client!

Below will be a video providing a step by step process of how to do what was explained above.
If you have issue with the steps above please refer to this video.