hl2.exe problem!

I recently reformatted my computer and installed Steam/CS:S and all its components. Once i did all that and updated what needed to be updated so i can play, i go and launch CS:S...a little screen pops up saying "Preparing to launch Counter Strike Source..." and nothing happens, it just disappears without actually launching the game. And just to make sure, i tried launching another game, and the same thing occurs. Now these games both need hl2 to run. So i go into my task manager and to processes, i realize hl2.exe is nowhere running.


Before i ever reformatted my computer, which is an XP, i had Steam and everything installed, and everything pretty much worked. I have no idea why it isn't working now and why my hl2.exe isn't running.


Is there any way i can get it back and to run it? :confused

 

You can try one of these sites to see if it may help you www.file.net/process/hl2.exe or www.techspot.com .