Pogoman
The first thing to do is too find out whether there is a partitioned OS System installed. If the following doesn’t work then you haven’t a partition and no harm will be done.
Okay so it’s hit the fan... Factory reset, give it a birthday, you’ve nothing to lose by the sound of it. It depends on a number of things whether this will work, e.g. how old is it, what manufacture.
Assuming XP O.S. Within partition. You’ll have no worries...this won’t work if you haven’t a partition, so give it a go....First switch off the offending pc completely.
Now switch on, immediately and continuously tap F11, or hold it down (This F number can vary (e.g. F12) with manufacture)
This will bring up, as the pc whines up, initially the factory reset page
Select the top option “a complete destructive reset”. The complete Factory reset option is what you want, don’t be shy, and don’t partially do the job.
Press okay...Don’t be nervous, answer a couple of question (e.g. English etc...yes)
It’ll then say something like, “this might take a couple of hours” go for that.
Now go make a coffee, come back in 30 mins and it’s as originally received, just outta the box.
You should install soonest a reputable antivirus program (Norton) and leave the pc on-line over night to auto up-date, this is can be time consuming, and best done whilst you’re asleep.
Good luck