Gmod stopped...booting

So Im not the one to ask for help, most of my gmod problems get solved by me. But one day, as I was playing, the game, er, stopped. It crashed. After closing it, I of course rebooted it…
“Preparing to launch”
then that window dissapears and nothing happens.
So I try the usual things, deleting client registry, cleaning gmod, and in the end bit the bullet and reinstalled gmod…but it still happens. What the hell? So I reinstalled it, but this time manually went into the folder and deleted everything…install it…it does the same thing?
Any assitance?

Specs?

Oh I assure you, I can run it. Like, seriously (All other source games work fine, I forgot to mention).

What changes have you made to your system lately? Have you restarted your system?

It started quite recently, around 2~ days ago, so yes, I have restarted my system, but I havent made any huge changes to my system either. This seems to have no real cause to me, which is why I’ve come to FP for help.

When you launch it, go into task manager to see if hl2.exe is actually running but just not responding.

It isnt running at all, the process doesnt start. It simply goes “preparing to launch”, and does nothing.

Erm, try verifying the cache, and if that don’t work do the following.
1.Save all the files you want (PHX, Wire, other addons and adv dupe files)
2.Go to the garry’smod folder (second one)
3.Rename it to anything else
4.Run Gmod.
5.Have new Gmod.
6.Reinstall addons.

Before you try anything (What above user posted, cleaning GMod, reinstalling, etc.), do the following:

1: Open Steam, right click on GMod, and click “Properties”
2: Click on “Set launch options”, in the box that pops up, type in “-fullscreen” (Without the quotes, of course)
3: Hit okay, and launch GMod