Buyer occupied home before sale deed, now bank loan rejected.

When sale agreement for property was made, due to goodwill n good intentions of owner(seller), buyer was allowed to stay in house that buyer wanted to own. Now, several months down line, property sale agreement expired, buyer did not get bank loan sanction, does not have lease agreement or rent agreement made with owner(seller). What right owner has to throw buyer out of owner's property? Just 1 vacate notice from lawyer enough? How much time court will give after issuing notice? Inorder to recover his (buyer) money, buyer can goto court only? Eventhough buyer's money is with seller, can seller throw buyer out so easily? Only out of respect, humanity, goodwill, trust, seller gave house keys to buyer just after completion of sale agreement only. Even before sale deed was done. Now, buyer living happily n demanding to seller, u pay my money in full (refund), i will vacate. Who has upper hand? Buyer or seller? No intentions of taking any undue advantage. Thanks.