I am not an attorney so you should consult one for legal advise
If the property sold on 2/21/2013, your landlord would have 21 days to provide you an explanation of charges to your deposit, items that they were charging due to damages etc (of course this would have happened when you moved out, not while you are in possession). The NEW owner in your case should be liable for your deposit as they are the new owners and would have made contact with you prior to deal with transfer of the agreement, inform you where to pay your rent from 2/22/13 forward etc.
They would also be required to provide you notice to vacate. IF the previous owner had given you notice to vacate let's say a week before it closed, it would be invalid upon the sale of the property and the new owner would have to give you notice to vacate. Those are all legal requirements which you haven't noted above.
As for a refund of rent, you are paying for the right to occupy the property, if you lived there up until the 21st, you would owe rent to the previous owner for the period up to the 21st and the remainder to the new owner up until you vacate.
NOW sometimes people say "sold" when they mean "pending sale", meaning the previous owner went into contract on 2/21/13 and they are in escrow, that would make sense why they are dealing with you even if they are no longer the owner. "Sold" is the day escrow closes.
It would be great if you provided an more solid update but if you need to talk to an attorney, I recommend Jonathan Stein in the Elk Grove area.
Regardless of all of this, a landlord is required to provide you an accounting of your deposit within 21 days of the end of your tenancy which appears to not have happened yet so you may be in a little grey area without more information to elaborate.
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