Brother(Little one) deleted most of Yahoo inbox, what to do!?!?

So my brother and I share an account when I don't feel like logging into mine and I told him specifically not to delete any emails without my knowledge and if they're important or not. Apparently he did delete the messages(Ugh...) probably the other day and they were not in the trash bin either. So I fill out the Yahoo recovery thing and unfortunately I did not get my emails back, so he had to have deleted them some more than 24 hours ago. I was reading something about an undeleter product which can be retrieved via a html file if your inbox WAS NOT overwritten by new mail(Which we didn't get). So does anybody know of any downloadable inbox retrievers or if it's even possible? Thanks in advance!