Under the Dept. of Education (ED) regulations, you must make 9 "on time" payments over a 10 month period of time. You can contact your loan servicer and discuss rehabiliation. If you don't know who your servicer is, or what the status of your loans is, go to the National Student Loan Data System website and look up your loans. You first have to set up an account.
What has been a problem in the past, has been that the loan servicers or debt collectors have wanted a higher monthly payment, than borrowers can afford to pay. But under new final ED regulations that become effective July 2014, if you cannot afford a regular payment amount, collectors must use the amount of your income-based repayment (IBR) payment, which should be much more affordable.