hl2 will not start up

[John Blaster]

ok, so ive looked for a solution to this problem for 2 weeks now and sent a few emails for troubleshooting through the steampowered site and they havent responded or anything so im just gonna ask this on here and hopefully someone can help. my system can run hl2 fine, i could play it before 2 weeks ago absolutely fine. but then one day i went to open hl2 and my screen goes black as if its about to load the game and then just jumps right back to the desktop and nothing else happens. the game doesnt launch, i get no error message, and no matter how many times i try to launch the game i get this same result. please help me figure this out.

 

[Trooper]

A few basic things here. What have you done to your system in the past few weeks?

A few things you might want to try here. Run virus and spyware scans. Update video and sound drivers (mobo while you are at it as well). Be sure to install the latest version of Direct X from Microsoft, then report back.

 

[Uber Kitty]

same exact thing happens to me, none of my games are opening and i have been playing fine for a while with no changes. It just started after the update I think.