When you buy a home with a mortgage the Escrow account is setup and money from your mortgage payments goes too that Escrow account to cover Property Taxes and Insurance costs.
When you sell your home and if there's any money left in the Escrow account the Lender will most certainly send the money back to you from your Escrow account since they're required too once you sell your house.
If they don't automatically send you money back from the Escrow account you should contact the bank to find out what is going on and if you're entitled to any money back from the Escrow account if there's any money left.