Is it just the start menu icon, does it change in Explorer? If you have show hidden files selected you may have deleted the desktop.ini for my music. If your OS is windows XP and .ini is missing copy and paste the following into a text document and name it desktop.ini.
[DeleteOnCopy]
Owner= ( add your name or owner name here, you can check .ini in my pictures to get proper name )
Personalized=13
PersonalizedName=My Music
[.ShellClassInfo]
InfoTip=@Shell32.dll,-12689
IconFile=C:\Program Files\Stardock\Object Desktop\IconPackager\Themes\IconADay\Icon-A-Day 1.0 Icon 29.ico
IconIndex=0
ConfirmFileOp=0
IconFileOld=C:\Program Files\Stardock\Object Desktop\IconPackager\Themes\RedGlassFolders\Red Glass Folders.icl
IconIndexOld=26