Disk error message seen after power outage

I've had no problems with installing and updating my Parallels program since I bought it about a year ago. Nevertheless, while I was using it last week my iMac was the victim of a power outage. When I restarted the iMac everything seen to be working as usual, but when I tried restarting the WindowsXP Virtual Machine I got an error message to the extent of 'Disk error has occurred...' I tried opening the virtual disk (winxp.hdd) with Parallel Explorer but I get a similar error, disk is corrupted. I definitely can't afford to lose the data I had stored in that drive.

How can I retrieve my data??

Any suggestions would be greatly appreciated!