First time home buyer has the money but not the credit.?

I have recently starting looking at buying a house and have a good bit in my savings with which to do so. I am looking at buying a foreclosed home and fixing it up not to sell but to live in. I have enough money to pay in cash but not enough to buy the house outright, replace the roof and give it a good coat of paint. I was hoping to get a mortgage to cover the house with a hefty down payment and use the money i had in my savings to fix up the house and still retain a healthy nest egg. The problem comes in when i find out that i don't have bad credit or good credit I just don't have any at all and the bank doesn't want to give me a mortgage even though the payments would be less a third of the rent i have been paying comfortably for 3 years. What should I do?