Don't do a repair, do a complete reformat as repair probably won't work anyway so don't waste your time.
IF ypu have the tech tools I'd do a back up of any files that you may want to keep. You can also try to DL (on a diff box) a copy of GHOST (to burn on a disc) to do this back up if you know how to use it and have other equipment available beside just your single computer.
GL