Once you realize your hard drive has developed some problems you should check your backups. Failed hard drive: check! Did not backup your data: check! Business proposal due tomorrow: check! Time to panic: double check!
First try plugging the drive into another computer to see if it will detect. OR run out and buy an external drive enclosure. Plug the drive into that and try it on a working computer.
If the drive detects (ie. assigns a drive letter) you're in business. You can probably run some software and get your data back yourself.
If the drive does not detect or even makes some noises, shut it down. Good news? You won't be doing that proposal tomorrow. Bad news you may get fired, and you will have to seek professional help. Speaking with a data recovery company is the next step. Be prepared because it won't be a pleasant experience.