One of the problems with a stiped RAID-0 is that if there is a problem with one drive the whole array goes down.
However it's not clear that is what has happened. Can you still get into Windows and if so what version are you running. Also is there just one 500mb partition in the array or more than one and are there any other hard drives on the PC.
Is this a hardware RAID (from the BIOS) or a software RAID running on dynamic volumes, etc, etc. The more specific information you can supply the better.
Have you lost data and is data recovery of pre-eminent importance?
It's possible there is a problem with one drive but unlikely if you can boot into the partition and a broken hardware array will normally inform you of the fact during boot-up.Is it possible one of raid drives failed?