mum brought window 10 pro for my old computer - as birthday present( which has had it) installed windows 10 on new computer(today) and try to active windows 10 pro but will not accept -License key or product id. is under her name of Ellie but her computer got hack ages ago and she lost access to her email address and had to have new ones. she cannot remember what email address it was that registered window pro 10 was with . so how do i activate windows 10 pro on my new computer? been paid for and everything.