This is where Windows "System Restore" comes in! System Restore is a component of Microsoft's Windows Me, Windows XP, Windows Vista and Windows 7 operating systems. It allows for the rolling back of system files, registry keys, installed programs, etc., to a previous state in the event of system malfunction or failure.(#1 Optional - don't stress if this feature is missing) Log on to Windows as an Administrator.
(# 2) Click Start, point to All Programs - Accessories - System Tools - System Restore.
(#3) On the Welcome to System Restore page, click Restore my computer to an earlier time, and click Next.
Or type or paste the following command in the Start - Run box then press Enter.
You can also access System Restore through 'Safe Mode' - your PC will walk you through it!