Rebuilt laptop and then installed Thunderbird. This was the process I presume you used. You ran Thunderbird the first time and this would have created a new default Profile. Thunderbird would then prompt to create mail accounts. Do not create any mail account because yo are going to use the backup information. locate the Profile folder manually or Help > Troubleshooting Information click on 'show Folder' A new window opens showing the contents of the current profile. Close Thunderbird - this is important. Locate your saved backed up Profile folder name. Usually called xxxxxxxx.default where the x's are letters and numbers. Open the backup profile folder name to see contents. It will show a load of folders and files including the 'Mail' folder. you would need to copy all the contents of the profile folder name - all of those folders and files - and then paste them into the new default profile folder name overwriting the default created files and folders. So you do not copy paste the actual profile folder name, you are copy pasting it's contents. If you did copied over the Profile folder name (not the contents), overwriting the new default profile folder name, then you would need to also manually alter the 'profiles.ini' file, so that it shows the profile folder name you pasted. So to understand what you currently have please post some images to show specific information. 1. Image showing contents of 'profile.ini' file. 2. Image showing contents of ' Thunderbird > Profiles' so I see the names of your profile folder names 3. Image showing the contents of the profile folder name which has all the files and folders including 'Mail' folder.