Buying a house with bad credit and no money down is possible but you likely won't be able to get a traditional mortgage because most if not all mortgage companies will require a good credit score and a down payment on the home mortgage.
You can however find rent to own homes by looking online or in the paper.
When you rent to own a home you may or may not have to put some money down and you sign a lease or contract saying you will make the payments on time and do upkeep etc on the property.
Sometimes you will have to put some money down and other times you may only need the first months rent payment.
The rent payments go towards the purchase price of the home and then at the end of the term you usually get a mortgage to pay off the balance owed on the house.