I went back to school to make more money, but now I can't find a job in the field i study for.What can I do?

I went back to school to earn more money. But once I finished school, it seems as if no one is hiring. The student loan people are asking for the repayment of my loan. Since I cant find a job in the career I study for, how will I be able to pay them back? I'm barely keeping above water with the job I have now. What should I do?