All the signs I see say 30 days. But call someone and make sure, depends on what your business is could be different. There are rules you have to follow or you will end up in trouble. I would give people more than 30 days, you don't want to get in trouble.
I sold a living room suit at a yard sale and I cannot get the buyer to come and pick it up. It has been six weeks. She will not answer when I call. She has told me on two occasions that she is coming and never shows up or calls. It is going on 2 months now. It is in my garage and we cannot get our cars in for the couch
In this case you could do as you please, she may show up and want her money back it will be up to you if you want to or not.