I owe more on my mortgage than I can expect to get if I put it up for sale and it actually sells. My mortgage is too high for me to continue to pay. I don't want to foreclose, but I can't make any more payments. I want to deed it back to the bank.

I need to know the process and how long it takes and also, what does this do to your credit score?

You are going to find out that banks don't buy homes, especially from their borrowers. I would talk with a real estate agent and get a second job until I could sell the property.