Your Thunderbird profile cannot be loaded. It may be missing or inaccessible. I tried uninstall, reboot many times. I believe it is because I accidentally deleted my Profile! How can I get to install Thunderbird without getting this message

Let's try an easy approach first, as it may work. If your backup is a copy of the appdata\roaming\thunderbird folder, just copy that thunderbird folder to overlay the existing appdata\roaming\thunderbird folder with thunderbird NOT RUNNING, and restart thunderbird. OK, if all you have is a backup of the profile, here's another, low-tech, approach. This is a bit clumsy, but I don't know your comfort zone. Do this. - Delete the appdata\roaming\thunderbird folder - download thunderbird again from thunderbird.net and reinstall it - start thunderbird, skip the option for new email address, and click help>troubleshootinginfformation - scroll down to 'profile folder' and click 'open folder' - EXIT thunderbird <== IMPORTANT - you are now in the profile. Copy your backup profile folder's contents and paste to overlay all content here - restart thunderbird