Please help?

[Fjcruiser X]

I'm new to this great site & would like to ask some questions on my situations here:

Bought this home in March 2007 for $625K as a primary residential.
- Down =$62.5k (my money) + Second =$62.5k (same lender).
- 1st = $500k + 2nd = $62.5k ( total finance= $562.5k)

- Now the value of the house is around = $460k ( means lost $100k+) in two years.

* I will no longer able to pay mortgage on this house because of my job & other financial issues right now.

Should I walk away? short sale? or forclosure?..Thanks in advance for any inputs.