First backup your profile folder. Make a copy of it. Ensure TB is closed If Windows probably here: C:\Users\YOURUSER\AppData\Roaming\Thunderbird\Profiles Then enter the "random named" folder, then enter the Mail or ImapMail folder, then enter the folder or folders you have for each account. Check the "INBOX" file size, if not zero, there is something there, you can check with something like Notepad++. You will also have a file called INBOX.msf (it has an extension and is smaller in size). Rename it. Start TB again, click the Inbox and WAIT see if the e-mails come up. If your inbox is huge TB will take time rebuilding the MSF (index) file. Look at your Hard disk LED, is it busy? Wait... if not, and it reports 0 messages at once, then there are recovery methods but will take time.