Hundreds of emails and my historic email folders have disappeared into thin air from my Mozilla Thunderbird account. There should be complete file folders of incoming email records in the Inbox for 2016 - 2020: the folders and contents have all completely vanished. And there's nothing left in the current inbox (for 2021) pre June 28th. The Sent box is a little better 2017 - 2019 emails seem intact, but there are very few showning for 2020 and only 2 for 2021 - both recent. I've check the MyBT server and it's showing exactly the same. BT's Technical Support say that this is not their issue and referred me back to Mozilla. I've tried the Thunderbird "Repair" procedure as advised - made absolutely no difference. Where do I go next???