HELP! Books not showing up on Kindle

I get epub books from the library, convert them to Mobi and send to my Kindle. It hasn't been an issue in the years that I've been doing it.

I was cleaning up my desktop and making folders to make it easier to search for things ... oh yea ... I moved the folder that all my calibre books were in and lost my entire index. I found a thing to rebuild the index and they all came back. Problem solved, or so I thought.

I've continued to send books to my kindle and some show up and others do not. I tried tonight to send a book 4x and it just would not come to my kindle. I started again, downloading the acsm, opening it and having it change to epub and then converting in caibre to the mobi and sent it again. Nothing seems to work.

I read that maybe the index hasn't caught up with it on the kindle, and to restart the kindle, which I did, and resent it again (and resynched) and nothing ... it doesn't come thru.

That was when I noticed that the last 4 books I sent in August have not shown up on my kindle fire. Any help would be appreciated!!!
*I've donated $$ twice to the support calibre heart*