Garrys Mod won't work! (Help needed)

Hey, so here today my Garry’s Mod crashed. And when I was trying to open it again, my screen goes black for some secounds, and after that my Garry’s Mod shuts down, and I get message “Garry’s Mod stopped working”.

Any help? I would really like to fix this problem.

So far, I tried reinstalling Garry’s Mod, Restarting Comp. Nothing happend.

Post specs.