All of my Steam games in my library are missing.
i still see the shortcuts to them on my desktop, and i can find them in C:\Program Files (x86)\Steam\steamapps\common
but when i click the shortcuts or the .EXE files, but i still can't play them.
when i go to their store pages, i see a message saying i already own them, for an example. when i try to repurchase Star Wars Dark Forces. i get a message saying i already own it. plus Steam says i am in offline mode but i can still access the Steam store. notes: i only have one account on my computer, i have contacted Steam support but have not get a reply yet.
has anyone else had this problem?

In your library, make sure you're displaying 'All Games' and not 'Media' or 'Favorites' or anything like that.

and not all programms as well :P

Also, click on your steam menu and choose "switch to online mode" or something like that.

If you're logged in the right account and if your filter is correctly set to display all games, you may have to refresh your client :

from support.steampowered.com :

Completely exit Steam and go to the folder called C:\Program Files\Steam\ (this is the default location for a Steam installation - if you set a different installation directory, you will need to browse to it).
Delete all of the files in this folder except:
The Steamapps and Userdata folders and Steam.exe (If 'exe' is not visible, look for the black and white Steam icon)
Restart your computer.
Then, you will need to launch Steam.exe from within the Steam installation folder, and not from a pre-existing shortcut.

Gaben ate them.

Can you see your Steam profile online through a browser, and is the games listed there?

If yes - delete and reinstall Steam (the client, not the games)
If no - contact support.

If nothing helps try reinstalling steam client.

i did that and it worked, thank you.