|When you say stopped working what do you mean?|
i assume you mean that they no longer launch the application they are a shortcut for, right?
Have you made any changes on your machine, or can you try to locate the applications that they are linked to?
if you right click the shortcut, then select properties, you should be able to see the path to where the exe is stored, see if the exe file is still in that location AND the file name is exactly the same as the 'Target' within the properties window.
Alternatively you can just create a new shortcut and delete the old one. But i would still want to know what the shortcuts stopped working.
Do you install all your software on a different drive by any chance?