First, check with your Realtor to find out whether the sales agreement you signed contained a provision about your finding a "home of choice" or similar language. That's a contingency that can get you out if you're unable to find a satisfactory home to purchase.
Second, ask your Realtor whether the buyers have complied with all the terms of the agreement. It's likely they were required to apply for financing and for insurance within x days of the contract's signing. It's also likely that they were required to provide the documents to a title company within x days. If they failed to do any of those things, then it's possible that the contract is null and void. (This isn't legal advice and I don't know North Carolina regulations; this is just advice to ask your Realtor about the requirements on the buyers and what your recourse is if they didn't do what they were supposed to.)
Third, ask your Realtor (the one representing you as a buyer) WHY your offers have fallen through? Have they just been rejected? Or have the sellers received better offers? Figure out what's wrong. Then consider, rather than backing out of selling your home, improving your offers so that one is accepted.
Finally, if you've decided to stay and you don't have an "out" as provided in the sales agreement, check with your Realtor and, if necessary, a lawyer.
Hope that helps.