Hey Gecko,
Since I do not know what situation you faced, I will just put out some general advice.
I believe most four-year institutions are finished with the enrollment process for the spring entrants. You might want to start looking into application process for the fall 2013 semester soon, as most undergraduate regular admissions application deadlines are rapidly approaching. If you intend on applying to an institution as a transfer student, then you probably have time until late February - mid March. Also, do take advantage of the Common App if you can.
You can also choose to start as a part time student and take few classes at an institution nearby where you live and just try out and see how it goes. This might also require some admissions process, I am not entirely sure.
Another option is taking classes through continuing education programs. Many universities offer continuing education classes. I believe that University of Florida has DCE (Distance and Continuing Education) program. As a flagship university, I would assume it is well-established and fairly challenging. I do not know how much help this could be if you are seeking a degree, but this could be a good starting place to test the water out!