If you can't find a buyer during the inspection period, let the seller know that the deal doesn't quite work at the negotiated price. Use whatever feedback you have gotten from your buyers to negotiate a lower price. If the seller isn't willing to go lower; notify them that you are cancelling the contract because it didn't pass your inspection. If they are willing to go lower on the price, get either a new contract signed or an addendum updating the price and extending the inspection period and closing.