Help! I screwed up my HL games

[Llama]

BASICALLY...

...for a while now all my old Half-Life mods (NS, Brainbread, Sven Co-op) havent let me play online, because my Client.DLL (Or something) (In folder Valve -> Steam -> SteamApps -> Myusername -> half-life -> ns -> cl_dlls) differs for the servers.
In a moment of stupidity I deleted the the file, working that next Steam restart it would download a new one...but It hasnt. So...

1.) What is the exact name of the file I deleted?
2.) How do I get a new one?

Help me ;(

EDIT UPDATE: Heh. My Client file was still in the Recycle bin X) but it still differs from the servers dll's. Why is that?

 

[Shamrock]

Why don't you uninstall Steam and then reinstall?

Verify cache of all game files.

 

[Llama]

Wont that delete all my games? (Im stupid X_X)

 

[Llama]

I unistalled and re-installed Steam, no change. Any more ideas?

(Sorry for double post)

 

[dream431ca]

Uninstall every single game manually (make sure to save your saved game files)

 

[coLE']

Back up all you cfg files and skin if you use any - then reinstall the whole package