Revover emails after rebuild mailbox

I have run rebuild for my mailbox and lost all my emails.

After an extended research in web I found out that I should spot the INBOX.mbox file and retrieve mails from it.

Although I found it, it was only 7.1MB. I had over 5.000 mails in my inbox, so probably the emails were also erased from INBOX.mbox.

I have no backups. Is there anything I can do?

Thank you in advance.