Many homeowners are finding they can’t refinance because they owe more than their home will appraise for.  Call your current loan servicer and find out if Fannie Mae is the end servicer.  If so, Fannie Mae has a program for “under water borrowers” and will refinance your loan up to 120% of your home’s value.  Obviously, you must still qualify for the loan.

FHA has the FHASecure program.

If you can’t make your mortgage payments and refinancing isn’t an option, the worst thing you can do is nothing.  A good place to start is Hope Now. 
Check out their website at http://www.hopenow.com/