Horrible Credit! What do I do?

I have horrible credit due to a medical situation that prevented me from working or paying my bills for about a year. As a result, all of my lines of credit have been closed. I have paid off all of my credit card debt and now need to pay off my medical bills. I have steadily been paying my student loans. What do I do in order to get an open line of credit so that I can begin to build credit again?