select read emails have disapeared. is my mail account hacked?

If you log in using the web interface for your email provider, are you able to see the messages there?

If you disable conversations in eM Client (Menu > View > Conversations) are the missing messages visible?


No means they are not visible through the web interface?

If you  did not delete them, and some other device connected to the same account did not delete them, then you need to contact your email provider for further assistance.