If you can't quality for the loans that is going to make it tough, not sure if impossible a lot depends on what you are willing to give up.
1) Pride: you can get a co-signer for Grad Plus that will over-ride your credit issues.
2) Money: you can agree to work in primary care in an under-served area and get private or government scholarships to pay for your school.
3) Freedom: IF you can qualify you can purse a military scholarship which will trade paying for school with years of service in the military. They are competitive and there are age & medical standards as well because you have to quality for an officer commission.
Outside of these about the only other option you have is marrying rich or winning the lotto. This process is expensive, many people spend several thousand just applying, it is not for the meek.