Need more information. What OS are you using? What version of Thunderbird are you using? Where did you get the Thunderbird program? Windows App Store, Snap, Flatpak ? Was it downloaded from the official website: https://www.thunderbird.net/en-US/thunderbird/all/ Need info because it tell me where the profile is likely to be located. Are you talking about an IMAP or Pop mail account ? A repair on folder does not delete emails, it repairs the *.msf index file to match what is actually stored in the * mbox file. If emails look like they disappeared then they did not exist, you were just seeing some header information. That can occur if an Anti-Virus decides to 'fix' an mbox file - they have no idea that a mbox file can contain more than one email, so if AV nukes the mbox file, the index is not touched, but is out of synch with reality. Gneral advise, do not allow AV's to scan profile files and folders or if you do never allow a fix. Also check the following as they can cause a block in accessing server. This needs checking before progressing to other causes. '''Firewall''' It might be controlled by the default supplied by OS OR it might be controlled by an Anti-Virus you installed. * Exit Thunderbird. * Access Firewall * Make sure the 'Thunderbird' program is set up as allowed. Do not just disable Firewall as that proves nothing is not desirable. * Confirm - Thunderbird program is set up as allowed. '''VPN''' Please check your computer to see if a VPN has been enabled. Many Anti-Virus products now offer VPN and in some cases it had been enabled by default. Servers generally do not like VPN because it attempts to hide your IP address and server may block access if it thinks you might be trying to hack the account. Switch off VPN. * Confirm you have checked computer for a VPN - also checked your Anti-virus to see if it now offers and has enabled a VPN - VPN is switched off. '''re web host provider,Hostgator,''' Have you recently moved to Hostgator ? Are your emails being hosted on a Plesk or Windows server? That would effect server settings. I presume you can logon to webmail account to see emails on server. So you know password works. Do confirm you can acess the webmail account. It would be useful to see what you are currently using for Account SEttings > Server Settings. Easy method - upload an image file which has the username/full email address edited/blanked out. check the username is the full email address. Good info at this link: https://www.hostgator.com/help/article/email-connection-settings