Do what
Corazon suggested ! It is the easiest way to get the lost icons back ... otherwise you may try to put icons back in C:\Windows\Installer manually using a program like resource hacker .... but that is really difficult .
One more easy choice of fix is using a
system image made prior to this scenario, not a restore point . So , first do as per
Corazon's suggestion, and when everything is normal, make a system image using
Backup Complete Computer - Create an Image Backup . So that in future you can fight such a situation easily.
Finally, prevention is better than cure . This mess occurs due to running some aggressive third party junk/registry cleaner. TuneUp Utilities is a well known victim

Avoid any of those programs, and use only
CCleaner for junk or registry cleaning . If you do so, I hope this situation will not occur once again