Hi there,
I feel you have been given very poor advice, you should always get any small problem checked before it breaks and cost big time. I feel that you may have two issues, one with the starter motor, as what you describe on stating sound like a faulty Bendix drive or a damaged drive plate. As for the loss of drive, this sound like an internal issue with the transmission, so you best find a trans shop for a quote om repairs.
mark (mhpautos)