Unfortunately there is probably nothing you can do at this point except learn from the experience. This illustrates the importance of chosing an Upfront Lender or Broker, see mtgprofessor.com to find an Upfront Broker/Lender.
Is there any chance your landlord will let you stay another 3 or 4 weeks? I would suggest you also immediately contact another lender to compare the lender fees and rates. Wells Fargo has been known to close mortgages in 10 days.
I am very sorry to hear your story Your remedies can normally be found in your contract. You did not state what closing date was n the contract . There should have been a "financing contingency" in your contract and also your Realtor should have worked for you to extend the contract closing date if possible. It boils down to your contract and state laws. I would seek the advice of a good closing attorney.
I agree with Scott, they may not ba liable, however they may be held accountable to a certain extent. Whether they are liable or not is for others to decide. Try speaking to someone at the Governing Body for Lenders, possibly the Mortgage Lending Division and see if they can help. They may advise you of your rights as a consumer.