Left 4 Dead 2 won't open.

[GuiltyOfPleonasm_]

I've been playing l4d2 for a while, I played it last night but I tried to open it today and it says it is running but doesn't open. I checked the task manager and it wasn't in the section with open windows but it was in the 'Show more' section, with all of my background tasks.

Thanks in advance for any advice.

[J.U.S.T-I.N]

restart steam or verify catche

[(/*◔ ◡ ◔*)/]

If you're still having an issue,

steamcommunity.com/sharedfiles/filedetails/?id=717945649

"Preparing to launch left 4 dead 2..." section