It is unlikely for you to have burnt out an IC with a refridgrator magnet. If you are running windows there will be a utility called check disk, check all the boxes and run that, be aware that it usually takes a couple hours, i usually do it overnight.
I find it pretty much impossible to believe that a fridge magnet would cause any problems for a disk drive. Every mechanical disk drive has a very powerful magnet INSIDE it which drives the voice coil head actuator. Some of the magnets I've taken out of disk drives can lift several pounds and they certainly doesn't cause any problems for the drives.
It actually takes a very intense magnetic field to affect the recording layer of a disk drive. The field produced by the heads isn't that strong, but it's concentrated into a very, very tiny area. The magnetic field from an ordinary fridge magnet is negligible by comparison. Contamination issues aside, I doubt it would affect the recorded information even if you tried to stick it on the surface of the platter.
I suspect a coincidence, or perhaps a static zap is responsible for the OPs problems...
I have 3 large magnets (fridge type) on the side of my case, like Hunter 315 says it's unlikly that would hurt the harddrive. I would suspect a bad sector or static charge (rub your sock feet on a carpet then touch a metal object (NOT your computer) you get zapped. That can hurt motherboards, etc...
what is static zap? never heard of it. what you suggest i do about it?
Static electricity is what you get when you walk across a carpet on a very dry day and then get a shock when you touch something metallic like a door handle. Static electricity can damage integrated circuits, and if it happens there isn't much your can do about it other than replacement.
But it's not all that likely that zapping the computer case with static electricity would hurt anything. Perhaps more dangerous would be zapping the leads of a cable what was connected to the system.
try the simple things first, to do a restore to an earlier time, Start, All Programs, Accessories, System Tools, System Restore, and pick a time before this started, if it stops then you know it was data corruption, if it doesn't well it was a coinsidence, but you will get a answer