Here's my thoughts....
If you had important info on the computer, its on you to remove it before you sell it. That's your fault. You leaving business material on a computer that you sold, is very poor business and again 100% your fault regardless who said or promised to do whatever.
to the buyer, this isnt walmart, if you want a refund dont buy from an individual. You picked the PC up in person, you were obviously satisfied with your purchase seeing as how you chose to pay for the item. If $500 is that important to you, i suggest you do more research before handing it over.
