|To get a working set of files for making a DVD, you also need the BUP and IFO files.|
If you lost them, there is an option. You can rename the .VOB files to .MPG. They 'should' play as MPG files. You could then combine them (in the correct order of course) and use a DVD creator program to remake the DVD, complete with its VOB, IFO and BUP files..
The three most important things in computing:
1. Backups, 2. Backups and 3. Backups.