If you have federal loans and can't afford your loan payments, you may want to look at consolidation or some of the income-based repayment plans available for most federal student loans. It is much easier (for you, and for your credit) to set up affordable payment plans before your loans go into default.
Affordable Repayment Plans for Federal Student Loans
Federal student loan programs have many protections, including affordable repayment plans. You can go here to figure out which type of repayment plan you may be eligible for, and to learn more about each plan.
You may also want to visit these other resources to learn more: