I have already given my advice re trying to fix the problem. If following these steps have not worked then it is certainly worth having an expert give it the once over to see if it is fixable and give you a diagnosis and estimate on how much it would cost to fix. That will give you a better idea of your options. Most repairers will do this free.

Re buying a second hand PC....I would not generally recommend this for most people especially someone who is not too PC savvy......in a lot of cases you are just buying someone's problems off them....and anyway PC technology advances so quickly you are buying something that is already probably well past its best and could even be cheaper brand new.

An entry level PC is pretty cheap nowadays so save up for that if the fix option is a no go.