Starter motors have a tendency to fail without giving any advance warning of them failing, had it happen on my E85 2.5, fine one day next day nothing. A couple of blows with a hammer and it sprang into life but failed after a couple of test starts. Far easier to take out and refit a replacement on the E85 took me about 20 mins. Lot more stripping down with the N52 engined versions. Source a replacement from your local parts suppliers, not sure what brands you have in the States.