Does it point to the correct directory? Right-click on the icon and go to properties. The directory would be the location listed in the "Target" box. Manually go to the listed directory and see if you can run your program from there. It may be that the directory to which the icon is pointing no longer exists, or that it has been moved.
simply going to the directory in which the program resides and right-clicking on the icon that launches the program and then sending it to "desktop (create shortcut)" should create a new shortcut with the correct target.