https://www.thunderbird.net/en-US/thunderbird/releases/   If you are missing data, I suggest starting over. That is, 

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

My suggestion is that you are several releases behind and updating may fix the issues. I do acknowledge there may be some quick fixes, but the upgrade path is safest. This is because THunderbird updates and changes the environment sometimes and it does that on the first version of each release. So, for you, there are many releases between 45 and 136 (or 127). The textbook approach would be to install the 0.1. version of each release in sequence, as that will update your profile appropriately. Here is a list of the series: https://www.thunderbird.net/en-US/thunderbird/releases/ If you are missing data, I suggest starting over. That is, - install 45 on the new machine and then do this. Here is the link for moving a profile in Windows when installed in default location: https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer here is the info in brief steps: # ensure thunderbird is NOT running on old machine # enter %appdata% in search window on task bar and press Enter key # this should open windows file explorer in Appdata\roaming folder # highlight the Thunderbird folder and copy to external media # ensure thunderbird is installed on second computer and NOT running # enter %appdata% in search window on task bar and press Enter key # you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it # start thunderbird and all should be there # continue with the above-suggested upgrade path. Prior versions are at https://ftp.mozilla.org/pub/thunderbird/releases/