Hey Lorianne. You need to get in contact with your attorney. He or She could advise you on whether or not the sellers can back out of the sale and if they can't, your attorney could advise you on the recourse/actions that could be taken. All situations are different, and that is why I advise you to contact your Attorney and Realtor.
I hope this answered your question! If you have any further questions, please feel free to contact me by the ways below.
De Vonte Williamson
Licensed Real Estate Salesperson
Proudly Serving Long Island
Coldwell Banker Residential
"I Stand Behind Getting You Results!"