If the bank takes your home through the foreclosure process, some states allow what is known as a deficiency judgment.  This can be obtained by the mortgage lender to satisfy the debt that remains when the proceeds of the sheriff sale are less than the amount owed on the mortgage.  If a deficiency judgment is obtained the lender can go after other assets including garnishing wages.

In actual practice, deficiency judgments are almost never pursued even in states that allow it.  The reason is that it usually makes no economic sense for the lender to spend thousands in court to go after a borrower who has already suffered a financial hardship.  It is better for the lender to just move on rather than lay out money for attorneys and collection expenses.  The bank has enough problems maintaining and marketing the property.  Going after a deficiency judgment would prove to be a useless endeavor.

If you are considering walking away from your home because you can not afford the payments, you ought to explore all of the possible options before making that decision.  The first thing you ought to do is contact the lender.  Your lender  may be able to change the terms of the loan to a payment that you can afford.  You could also negotiate a "Deed in Lieu of Foreclosure" in which case there is no foreclosure and you simply deed the property to the lender.

Often the bank will make an offer to modify your loan that may not be the best possible deal.  You can hire a professional to negotiate on your behalf.  Often they can get a much better deal from the lender.  An attorney, CPA or licensed mortgage broker can perform this service for a fee.  Do not pay an advance fee, rather pay for the service once it has been completed.  Non-profit and free services are available from HUD certified housing counselors as well.