• What OS are you using ?
• What version of Thunderbird are you using ?
• Are you talking about a Pop or Imap mail account ?

You say "it seems that it tries to connect with server but it cant."

• If you cannot receive nor send - when you click on 'Get Messages' do you get an error message pop up ?
• If yes, what does it say OR better still upload an image of the error message.

In the meantime please check the following because it can block access to internet, so it's important to rule them out.

Firewall: Access Firewall - it might be the default on computer or controlled by an Anti-Virus program. Set up Thunderbird program as 'allowed' so nothing gets blocked.

• Confirm Thunderbird is set up as allowed program.

VPN: Check computer for a VPN. Some Anti-Virus products now offer a VPN and I have come across some people who did not realise one had been enabled. Switch off VPN (or create split tunnelling and set it up for Thunderbird to use). Gmail does not like VPN as it attempts to hide your IP address, so gmail decides you might be hacker so it auto blocks access.

• Confirm VPN is switched off

In Thunderbird check the cookies are enabled.

• Settings > Privacy & Security
• Web Content
• Select 'Accept cookies from sites'
• Click on 'Exceptions' button
• Enter this : https://accounts.google.com
• Click on 'Allow
• Click on 'Save Changes'

Confirm all three of the above have been checked, allowed, switched off etc.

Also check the following: How much server quota has been used ? If you have used up server quota then gmail cannot receive emails as there's little space. If you logon to the gmail webmail account via abrowser - do you see new received emails which have not been downloaded to Thunderbird? Gmails quota is not just emails, it's everything stored on server including eg: Images.

Hi

thanks for your help. As I wasn't sure to know how to implement your instructions (I could not access to Privacy & Security on settings), I've decided to upgrade from version 140.6 oser to version 146... and now it works again!!!! Thanks again for your support and help!