What contingencies did you put on your offer?
Within what period of time?
If you have not cleared or signed off on all contingencies within a certain period of time, you may be able to back out and get your deposit back.
REOs generally provide their own contract in addition to the traditional CAR (California Association of Realtors) contract, so this may require more scrutiny.
You would need to refer to your purchase contract. It should state reasons you can cancel contract without losing your ernest money deposit. You might want to talk to your Realtor too.