No contact at all in three weeks? . Have you tried to contact her broker? Maybe your agent is ill or had some kind of major emergency.
Working with buyers requires a lot more time than working with sellers. You need a buyers agent who is not too busy to cater to the unique needs of a buyer.
I would like to know what documents you signed. Did you actually put an offer on a property? Sometimes with REO's the listing side does not counter all offers, some offers may not get any reply at all. They simply select what they think is the best offer and move on. If this is the case your agent should keep you posted on what's going on.
As for your deposit check it should be held uncashed at your agent's office until you actually have an offer accepted. You are not at risk of lossing any funds at this point.
Try not to get discouraged. Stay engaged in the home buying process even if you have to move on to another agent.
Best of luck to you,
Kawain Payne, Realtor