I have this issue with one of my outlets in a room that might not be grounded (no crawl space and concrete underneath so believe it was a garage that was converted into an extra room and the guy flipping the house was rather shady-bought the house back when it was a seller's market). Anyway, the issue is that when I plugged the Christmas tree lights into the outlet, they were very bright and then after a day or two they were burnt out. My question is, is this just a matter of the contractor taking a three-prong appliance outlet probably used for a window a/c unit and just putting a normal outlet on it? Can I just switch the breaker and fix the problem?

I'm a beginner to home improvement, but have done minor things like switch a breaker. I don't really know what things I need to tell someone to get an answer, so please ask and I'll give all the information I can!