Mary, When you made your offer, was it submitted to the seller in writing on a purchase contract that you had signed? That would have been the way to do it, but when you said that you talked to the seller and were just waiting to sign the contract, it made me think that your original offer was possibly just verbal. Not knowing exactly how your offer was originally submitted, I'll just say that in a real estate transaction, everything needs to be in writing. You would not have an accepted offer until both the buyer and seller have agreed to it by signing it. Then, assuming that your lender has already pre-approved you as a borrower, he or she would begin the approval process for a loan that's specific to the fully-executed (signed by both buyer and seller) contract.
I hope this helps; however, please feel free to either call or email me with more specific information so I can tell you exactly what I think you should do. I'll be happy to help.