Hard drives are a magnetic memory medium so there is going to be damage to the files on your hard drive if the powerful magnet came too close to the hard drive. Get a recovery disk set from the manufacturer (usually not too expensive) and first try a start up repair and see if that helps. If it does not work then try accessing your hard drive from a Live Linux disk and see if you can back up any of your personal files and then do a full factory restore.
You have to be a little bit crazy to keep you from going insane.
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