It may be difficult getting a mortgage, and the advice below is fine if you go that route.
However, there are all sorts of seller financing out there. Ordinary seller financing, contract for deed, land contract, lease-option, lease-purchase. Then there's buying subject to the existing mortgage. Or you can work with an investor or a friend/relative on an equity share arrangement. I've explained these techniques in previous posts, or you can Google them.
Just make sure that you can make the payments. And involve a lawyer in the process to protect your interests.
Hope that helps.