What can I do if the management company I rented from lost?

the home that I am renting? Can I get my security deposit back? I call them but get no answer nor a call back? I found out that a mortgage company purchased the house by paying the back taxes and forfeited the loan the homeowner had taken out. What can I do? Is there a way I can purchase the house from the mortgage company? Helpful advice needed here. Thanks :) I forgot to add they gave up the house last year in September. I am still living in the house.