Hi Retepdrallub,
Thanks for taking the time to contact us via the Community. It's lovely having you on board with us in the Forums. ⭐
We're sorry to hear you're having issues logging in to your account via your desktop PC. Just to clarify, are you referring to My VM or your email account?
In terms of the Thunderbird client, you'll need to generate an app password in order to access mails through a client or app. Please log in to My Virgin Media here > Click on Account settings > Identity & Security Settings > Select Manage your products > Select Manage email app password > Click on the blue button 'Get New Password'. Follow the onscreen prompts to verify the account and you'll be given a password which looks like: mail-horse-yellow-panda and you should note this down.
On your Thunderbird client, use your VM email address and the new password and this should resolve that side of things for you.
Many thanks,