Missing hdd

I was using Parallels with no problem, quit it, put my Mac to sleep and a couple hours later opened it up and tried restarting Parallels. I get an error saying the winxp.hdd is missing. In the Parallels/Windows XP/ folder there is no winxp.hdd, but there is a single .sav and and a single .pvs file, as well as an empty Windows Applications folder.

I have a Time Machine backup that's four days old. But I have done quite a bit of writing since then.

Is there a way to salvage the last four days of work?