These links might be worth looking at:
http://www.wikihow.com/Recover-Deleted-Files-from-Your-Computer
http://www.piriform.com/recuva
Everyone should copy their Opera profile (which includes the bookmarks folder) to another location on their computer, preferable an external drive. (flash drives are great). For Opera 28, just click on the Opera Menu and then click on About Opera to find the location of your profile.
In Opera 12, the location is in the Help menu, and then About Opera.
With that profile, saved periodically to an external drive, there would rarely if ever be a panicked "lost bookmarks" query. I'm assuming, though, @gcatsailor that you're asking the question because you didn't.