You can get to Window 7's icon cache and have Windows 7 build you a new copy, You will need to delete theIconCache.db file and restart your computer in order to allow Windows to create a new one.
To rebuild your icon cache:
Close all programs
Click Start, then type CMD into the Search programs and files window.
Right click on the CMD program that is displayed above and selectRun as administrator.
Navigate to C:\Users\<your user name>\AppData\Local. This can be accomplished with the command:CD /d %userprofile%\AppData\Local <enter>
Delete the IconCache.db file that resides there. e.g. DEL IconCache.db /ah<enter>
Close this command window and restart the computer.
If your icons do no immediately return after the restart, simply restart it agin. I've never had to restart more than once myself, but I've heard of others having to restart two or three times. This is most likely due to having programs and/or Explorer processes running before the first restart, e.g. not following step 1.