Cleanly reinstalling Steam
If you are here because you want to fix a game problem, stop what you are doing and validate it. Validation does everything uninstalling does (except change your settings, which doesn't require reinstalling either) in a fraction of the time and with a fraction of the bandwidth.
If that doesn't apply then here is how to perform a proper, clean reinstall of Steam:
- Write down your Steam Account name and password - you will need them to log back into Steam once you have reinstalled
- Logout of Steam if you are able to do so
- Exit Steam
- Move SteamApps out of the Steam folder. This is the folder that holds your games so you want to keep it!
- If you are having problems with a specific game, delete it's folder from SteamApps/<account> - Uninstall via Add/Remove programs, if you can
- Restart if prompted
- Delete Steam folder if it still exists
- Hit windows key + r and type regedit
- Delete HKEY_CURRENT_USER\Software\Valve and HKEY_LOCAL_MACHINE\SOFTWARE\Valve
- Download and install a fresh copy of the Steam installer from http://www.steampowered.com/download/SteamInstall.msi
- Run the installer
- Exit Steam before you first login
- Move your SteamApps folder back