Do you mean just shortcuts or the .exe files associated with them?

For example, if you use Windows Explorer to navigate to C:\Program Files (x86)\Internet Explorer and open "iexplore.exe", does Internet Explorer open up properly?

If it is only the shortcuts that fail, (.lnk files), then use the method in the link below to restore the default .lnk file association;

http://www.sevenforums.com/tutorials/19449-default-file-type-associations-restore.html

Hope that helps.

Mark