K.P.
You may need to take out a personal loan for a significant portion of the remaining balance (to make up the difference b/w the principle and the appraised value) and go from there.
Essentially, if you have $200,000 remaining on the principle of your home, but it only appraised for $120,000 you would need to apply for an $80,000 personal loan and give that $$ to the mortgage lender so that what you owe equals what your house is worth, then refinance the remaining balance.
This will mean making two loan payments each month, but you will stay in your home and not be in default with your mortgage.