I have no idea what happened but that is a drastic change.

You could ring ebay to check what is going on.

If i were in your shoes and had sold a lot at that far too low price, I would send a message to every buyer & explain that something had gone wrong with your account and you needed to cancel all weekend sales. I would send a cancellation notice.

Some people may accept it, if I were a buyer I think I would have some sympathy for a seller in that situation.

Some buyers will probably kick up though and your ebay account might also take a battering with defects or whatever, but really, you can't afford to lose all that money & you don't have to carry through with the sale if the price was a mistake. So don't.