If there is a hardware failure, it would most likely fail under Knoppix also. You can try Knoppix and see what happens. Knoppix can usually read from XP partitions quite well, but if the drive is encrypted, you may be SOL. I would also try to see what the hardware issue might be and see if there is a way to correct it. The hard drive can also be removed and read in another system if the drive is not affected. The drive could also be corrupted. XP has sometimes had a habit of unexpectedly doing just that. If so, the recovery of your data is now a different issue. You may be able to recover the drive if it is mechanically sound. There are tools that can repair the MBR and more.