Quitting work and getting paid out unused vacation time

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Does anyone know anything about this? 
So my Fmla time has come to an end and I planned on having my employer pay me out some of my vacation time. At first they said they could approve it, now when I called them back inquiring about my pay and where it was they said I have to return to work before they can pay out any vacation time. I did not plan on returning to work and was hoping to just get this final pay and be done. 
Not sure if it matters but I went on maternity leave end of March and my vacation time renewed May 23. Also my job is out of Michigan. Trying to decide if I should go back for a to weekend to get my vacation pay then put my two weeks in or chalk it up as a loss. Even still they have not guaranteed that they will pay me out right away.