Check out DaveRamsey.com, and start listening to him; make a budget and stick to it. Get the "The Tightwad Gazette book(s) and read through those -- an amazing amount of frugal information that might make the difference between you keeping and losing your home. The most important monthly expenditure is food (not eating out -- "rice and beans" kind of food); next pay your electric bill (but don't keep the a/c so cold); keep gas & insurance on the car so you can work and go places; pay your mortgage; everything else is secondary to that, especially credit cards (drop your cable bill and cell-phone coverage to the bare minimum, or drop it entirely -- that sort of thing). Is there any job you can do part-time that will get money coming in? In-home day-care (for children at your home or seniors at theirs), cleaning houses, delivering pizzas, after-school tutor, driving a bus for the elderly and disabled? Have a garage sale, sell stuff on eBay & Craigslist or through your local cheapcycle network. You may already be doing this stuff to the best of your ability, but I'm trying to brainstorm with you. Could you rent a room to someone you know (someone reliable -- not some kook) to help meet the mortgage temporarily, while your income comes up?
If you can't pay the above bills with the money you have coming in, and you can't get any more money coming in, you will have to sell your house or risk foreclosure. If you sit down with your budget and realize you can't keep the house, and you put it on the market and you can't sell it for what you owe on it, you may have to short-sale it. If you do that, try to get a short-sale "without recourse" (meaning they can't sue you for the difference). If you can't keep the house it's best to sell it for what you owe on it (or more); if you can't do that, it's best to short-sale it without recourse; if the mortgage company won't let you go without recourse, the next-best thing is to short-sale it and owe the difference (better to owe $10,000 than $100,000!); and if you can't sell it at all, they will force you into foreclosure. If they foreclose on you (I think you have to be 6 months behind before they start the process, and it usually takes several months to complete it -- so things may turn around financially for you in that time), they'll sell the house for whatever they can get, and then sue you for the difference, but that part may take even a few years to work its way around to you.