You can easily do that from your Steam Settings panel. To make sure you have all the files needed, restart your PC and then verify your game files.
If you had some type of backup, you may be able to pre-install those It isn't hard to reinstall Steam even though you say you have already done that, the time is taken by downloading the game files. EDIT.You can reinstall it a 100 times, but if you don't have antivirus exceptions for Steam and games, the same thing can just keep happening How to Fix the Windows Cannot Find steam
Did you make sure to exclude Steam.exe from your antivirus software, or other security software ? If security is quarantining the file, then that can be why Windows can find it. Steam and Avast simply don't get along well. It's highly likely that your computer has been infected by a virus that is. What Causes the Windows Cannot Find Steam.exe Error? Solution 1: Scan Your Computer for Malware.
