I rented a house for 3 years. I did sign a lease and gave a security deposit. My landlords sold the building I was living in. Within a month after the sale, my new land lord raised the rent with the option to vacated the premise instead of paying the increased rent. I paid one month of the new rent and gave a month notice that I would be leaving. My problem is... my old landlords claim they gave my security deposit to the new landlord... so he could pay it to me once I decided to leave. I can't get in touch with the new land lord. So anyway... who should pay me my deposit?

The new landlord.

First of course the new landlord has to honor the old lease, they can not merely change the terms of the lease after they buy it.

So the only way he could change the amount you pay is that the lease was over and you had went onto a month to month rental. A new owner is obilagated to accept and honor any lease on the building.

Next on your question, at closing the old owner gives credit for any deposits and other credits on the property.

So the old owner has nothing to do with it at all anymore.
The new owner will be liable to pay you.

Most L-T laws REQUIRE that the old landlord acknowledge what happened to your deposit when the property transferred... if you did NOT get such a notification, sue the OLD landlord and find the NEW landlord by researching the city/county tax ownership records... sue them both in Small Claims Court.

You said that you gave a month's notice. Where did you send the notice? If you can't locate the new owner, it is going to be difficult to sue him in small claims court. That is, by the way, the correct answer. Suing both the old and new owner will force one or the other to bring the closing papers to court. Actual dollar bills (security deposits) didn't change hands. It was all on paper in the closing statement. It is the new landlord that owes you the security deposit. If he hasn't purchased rental property before, he may not even know it. Call property records or the auditor's office in the city/county of the rental property. With the correct address provided, they will be able to give you the name of the landlord and the address where they send the tax bill. FYI: Check the tenant/landlord laws for your state. Landlords are required to either return the security deposit or tell the tenant how they used the deposit within a set number of days (usually 30) or the tenant can file a civil action in small claims for twice the amount of the deposit.