My home went into a Sheriff sale & I received a 1099-A form from a 2nd mortgage loan.
Box 4 is HALF of the value it was worth at the time of the loan, with no appraisal to verify that number. Am I liable for the amount claimed in box # 2? Am I required to claim that number as income?

You don't mention whether box 2 is bigger or smaller number than box 4. If box 2 is greater than box 4 it would generally be a taxable event (your income is the differece between the two figures, which is the amount of loan that was forgiven). However, if you declared bankruptcy then it is not taxable. The good news is that if this was taxable the lender would have sent you a 1099-C, not a 1099-A. So I can only guess that either box 2 is less than box 4, or you declared bankruptcy- is this correct?