Enforcement of violations by employers of the Americans with Disabilities Act (ADA) is done by the federal Equal Employment Opportunity Commission (EEOC). The EEOC is a independent federal agency and not part of the federal Department of Labor (DOL). Note that you must first file a timely complaint with the EEOC before you may file a lawsuit for an ADA violation. Information on filing a complaint with the EEOC may be found here: https://www.eeoc.gov/employees/howtofile.cfm
Employer violations of the federal Family and Medical Leave Act (FMLA), on the other hand, are enforced by the Wage and Hour Division (WHD) of the DOL. It is not required that you file a complaint with the DOL prior to filing a lawsuit for violations for the FMLA, but it may still be useful to do so. Information on filing a complaint with the WHD is located here: https://www.dol.gov/whd/howtofilecomplaint.htm

