bricky526 said

All other folders and sub-folders are intact. I am using windows 7

If my Inbox is empty it's because no-one has sent anything to me. I take it from your complaint that you eave messages in the Inbox and now they have gone?

Do you use any other devices to access this email account? A phone or tablet, another email client?

No other devices. My email is forwarded from my internet provider. I have not had any problems with Thunderbird until this afternoon. I have 2 email addresses on it and the inbox on the other is fine.