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:

1. Logout of Steam if you are able to do so
2. Exit Steam
3. Move SteamApps out of the Steam folder. This is the folder that holds your games so you want to keep it!
4. If you are having problems with a specific game, delete it's folder from SteamApps/<account> - Uninstall via Add/Remove programs, if you can
5. Restart if prompted
6. Delete Steam folder if it still exists
7. Hit windows key + r and type regedit
8. Delete HKEY_CURRENT_USER\Software\Valve and HKEY_LOCAL_MACHINE\SOFTWARE\Valve
9. Restart
10. Download and install a fresh copy of the Steam installer from http://www.steampowered.com/download/SteamInstall.exe
11. Run the installer
12. Exit Steam before you first login
13. Move your SteamApps folder back