MISSING TEXTURES TUTORIAL:
(IF YOU HAVE CSS, JUST SELECT THE GAME IN THE GAMES TAB)
Step 1:
Go to this link: http://kajar9.wixsite.com/cscheater2/downloads
Step 2:
Find the CSS tab and click MEGA Game Content.
Step 3:
After it finishes downloading, open the WinRAR file.
Step 4:
Make a folder called CSS Textures or something like that, doesn't matter.
Step 5:
Extract everything from the WinRAR file to the new folder you just made.
Step 6:
Copy the folder that we just made.
Step 7:
Go through your program files (x86) and find your steam directory.
Step 8:
Open the steam folder, go to steam apps, then common, and click Garry's Mod.
Step 9:
Click the second Garry's Mod folder and open add-ons.
Step 10:
Paste the CSS Textures folder from earlier into add-ons.
That's basically it if this confused you go to this video: https://www.youtube.com/watch?v=yaL7gISscEY
If something didn't work or I skipped a step, let me know.