Can the buyer of my laptop demand a refund?

I sold a Lenovo laptop last night through a listing on Craigslist. The laptop was in complete working order last night when I sold it, but this evening the buyer contacted me saying that it was now 'not responsive' and that he can't get it to do anything. He said he was going to try to re-install Windows on it and get back to me tomorrow, but if it didn't fix the problem he would request a refund.

Am I even obligated to give him a refund on the computer? I sold it for a lot less than I probably should have, and I have never had a single problem with the computer over the two years I have owned it.

It just seems a bit sketchy that now it seems to be having all of these problems, and the fact that he is re-installing Windows on it bothers me too.

I live in Nebraska.

Added (1). I meant to say, a listing on Facebook. A simple post on a Facebook group.

If it was working when you sold it, Then you don't give his money back unless he can prove it was tampered with, meaning You knew something was wrong with it and you didn't tell him, for example, You dropped the computer and it still works but not like it did before you dropped it, so ill sell it before it quits working completely, Now if you told him you Dropped it and he still wanted it, Then No, It was sold as is, Now if he asked you if it was ever Dropped, Got wet, Overheated, and Your answer was No to all, and he takes it to a computer repair shop and they tell him it was dropped, Then you will be giving his money back.

Careful he might be a scammer. Check out the craiglist website that you sold it on, and see if it is necessary for you to refund, or call up their customer services. Keep in mind he said "request" a refund and you can deny a request. You sold the laptop with the knowledge that it was working perfectly well for you, so as long as it was your in the clear.

Tell him tuff luck, as-is as you never told him about a warranty or x amount of days to get refund if he doesn't like it

Nope, once he takes possession, it's his. Buyer beware and all that.

Certainly once he alters the computer by reloading the operating system it is his.

Of course, you have to take into account your standing with the group you are with, if that's what it was. Giving a refund to save your reputation is a choice you make. You are not compelled by law to warrant your used product or offer a refund.

Yes, of course.