That happens. That's one of the reasons we backup (most of us anyway, and those who don't find the time comes they regret they didn't).

The Windows DVD boots if 3 conditions are met:
1. It's bootable and undamaged.
2. The BIOS setup is to boot from the DVD before trying to boot from the hard disk.
3. The drive is functioning correctly.
Only you can decide which of three isn't met. I can't from a distance.

To recover data yourself try the programs mentioned in http://forums.cnet.com/7726-7588_102-3105734.html (click on the "Click here" link in the 4th line to see the whole thread!). Be sure to run any program you try in demo (read-only mode) first, because if you let them modify the disk any subsequent program would find the mess even greater.
Or find a reliable data recovery company and pay them to do the job. It's their daily work.

Kees