If you are unhappy with your current situation then the best thing is to improve it. If the problem is with the unit itself, then some simple, CHEAP redecorating may make a big difference. If it is the complex, the location, or the cost then you should find out what its current value is. You can ask a Realtor such as myself to do a FREE Comparative Market Analysis to determine how much you could sell it for in today's market. As stated in previous answers, you probably got a great deal on the property. This should allow you to walk away clean from the property or with a small profit that you can apply to a new place.
There is a chance though not as great that you could use it as an income property.
First question is did you use a buyers agent? You should always use a buyer's agent to help you get answers to all your question to make you comfortable. A buyers agent works for you and there are many question they should help you get answers too. Are you comfortable with the payment, is the home close to your work, do you have family in the area, how is the school system if you have children? These are just some of the question a buyer agent will help you get comfortable with your decision.
I don't know why you now wish you hadn't made the purchase. If it's financial, then the best you can do is hang in there, stay current with your payments, and wait for the market to at least stabilize, and then try to sell. That, however, is most likely several years away.
Whatever the other reasons might be, there isn't much you can do but make the best of it.
Of course, you could always look into renting it out if the numbers work. Call in a Realtor, and find out how much you might get asa a rental. If you can cover your monthly payments then that might be one solution.
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