So due to an issue with a corrupted registry, I've had to reformat my c: drive. Thankfully, all of my Oblivion files were on Local Disk D, and I managed to save the My Games folder too.

I'm just wondering on what I should do once I get my PC back. Will Oblivion still manage to work?

You''ll have to reinstall your game so that your new registry gets updated. Otherwise your system won't know where the game is. Any mods you had before should be fine though.