If you had a mortgage on the property, then the lender will be sending you a 1099-C Forgiveness of Debt to report the amount of borrowed money you did not pay back. You will be taxed on that money too.
On that same front, it may be years before your get the 1099-C too. If the lender sells the property and gets "some" of the money back they lent to you, then that will reduce your taxable amount. If they get it all back, then you'll never get a 1099-C and don't have to worry about it.