Why my Emails automatically disappearing / deleting form Mozilla Thunderbird?

Question

Facing problem with emails with my Inbox. The older mails automatically got disappear / deleted form my Inbox, I don't know why?

How can i fix that and recall all deleted / disappeared stuff back in Inbox.

Using OS : Windows 10

Answer 1

• Please go through the settings 

• Right click on mail account name in Folder Pane and select 'Settings'
• If pop select 'Disc Space'
• If Imap select 'Synchronisation & storage'

• select 'Don't delete any messages'
• click on 'OK'

• Right click on Inbox folder and select 'Properties'
• click on 'Retention Policy' tab
• make sure it says 'Use my account settings'

• click on 'General Information' tab
• Check to see if folder index is out of synch with actual storage,
• click on 'Repair folder' button
• click on 'OK'