Unfortunately my Windows was gradually " breaking down". Fortunately, I was able to save most of my data. However, I am having a huge problem in getting Thunderbird to recognize the old profile. Question is what am I doing wrong or what has gone wrong? I use Windows 7 professional. And Thunderbird 52.9.1 Links I have read to try and resolve this problem. Not necessarily in this order. Rebuilding the Global Database https://support.mozilla.org/en-US/kb/rebuilding-global-database Profiles - Where Thunderbird stores your messages and other user data https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data Moving Thunderbird Data to a New Computer https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer Enclosed are screen shots of the opening of TB, Then of all the files I have in C:\xxx\xxx\AppData\Roaming\Thunderbird\Profiles\xxxxxxx.default As Can be seen that by the size of the files I do have ll the old emails and address book there I hope this information is enough to help you to help me solve this.