well i don't think your explaining it right... for the first thing i got to ask is does it not open any programs? if not then ok lets move on.
next does the left side work for everything else once you do open ? if so lets move on.
next, When you full up "My Programs" and you pick one and left double click does it act like its going to start but don't? if you answered yes to all of these then yes you have deleted one or more files that you shouldn't have and yes to bring the double click feature back on for your programs you will have to reboot Windows.
i know this sucks but you are the one that was fooling around with stuff you didn't know was... Right????????????
ok now remember next time not to remove some stuff and it is possible to have it happen with a registry cleaner too..