Sent mails disappeared!!!!

Hi,

Since Mavericks I'm really fed up with my mac's Mail program! It's a piece of crap! Shame on you Apple!

My newest problem is that I can't find my Sent emails! I use AOL as my primary email, and for years, I've been able to search all my sent emails. I did not delete these sent mails as they were important. Now most of them are gone! I can't seem to find it. Where are they? How could I get them back? There were important mails, conversations in them so it's important me to get them back...

(In my settings in the Mail program I set it as to Never delete any mails... but now it happened..)

Thanks