Go to fafsa.ed.gov and check whether you meet any of the limited special circumstances under which you might qualify to file without parental information. (See link in Resource section.) The site says you may qualify if you can't provide the information, are homeless or are seeking an unsubsidized loan.
Complete information on the FAFSA about you and your finances, and skip any questions about your parents.
Sign your FAFSA with your personal identification number and leave blank the PIN for a parent. You can submit your FAFSA without parental information, but it will not be considered complete. Because your FAFSA is not considered complete, your expected family contribution will not be calculated. The EFC is the index colleges use to determine how much student aid you are eligible to receive.
Gather as much written evidence of your special circumstances as you can. You will have to provide documentation to the financial aid administrator at the college you seek to attend, to verify your situation. Special circumstances might be: A parent is incarcerated; you don't live in the parental home because of an abusive family environment; you don't know where your parents are and can't contact them (and you have not been adopted).
Contact the financial aid administrator at the college you plan to attend and present your special circumstances. After reviewing them, your FAA will decide whether you must provide parental information or if your circumstances allow you to proceed without providing parental data. Your FAA's decision is final and cannot be appealed to the U.S. Department of Education's student aid program.
Return to your FAFSA application and complete the form based on your FAA's decision, to generate aid eligibility and expected family contribution information.