You can not delete the "Local Folders" built in account. So using that logic everything will be in the trash on local folders... unless she held shift to bypass the trash folder.

Sorry that doesn't solve the problem. She wouldn't have pressed the shift key knowingly as she is unaware of that process. The Deleted folder is empty. when i go to troubleshoot etc. and look at the local folders section, there is no mention of the sub folders that are lost. does this mean that they have been deleted? if so is there any way of recovering them? what type of files would they be so I can scan the hard drive for these lost files? hoping for a successful conclusion.

Update. It seems that my wife created her subfolders from the "deleted folder" under "local folders". She then right clicked the "deleted folder" and clicked empty, then confirmed not realizing it included her subfolders. Any way back?

I was going to say, there is no deleted folder, there is a trash folder. But seriously. thee is no way back in Thunderbird. There might be a way using low level undelete tools for windows. But that is really beyond the purview of this forum.

There is a chance shadow copy is enabled on your device. so see the instructions here. https://wiki.carleton.edu/pages/viewpage.action?pageId=9968143 If it is enabled it is the easiest approach. But do not hold your breath. It uses a fair bit of space and cheap manufacturers do not renable it. They get away with smaller hard disks.

https://www.howtogeek.com/169344/how-to-recover-a-deleted-file-the-ultimate-guide/ This article discusses low level recovery, look at the part about recuva. Just never use it to remove applications. It does an excellent job of completely deleting Thunderbird mail when it is used. Not what most folk want. But as a file recovery tool it is probably as good as any. Note your "risks" to getting your files back increase the more the machine is used and the more files are written.

Goto the help menu in Thunderbird. click on troubleshooting information and then click the show profile button. this will open windows file manager showing the path to your Thunderbird profile. The path will provide information about the location of the files you want to recover.

Make sure Thunderbird is not running when you fiddle with the profile folder. I also suggest you copy it (the entire profile and sub folders) to a USB drive first in case something with the recovery goes very wrong. That way there will be a way to recover.

Many thanks for your help. I have now found a way round the problem. I have downloaded her Gmail archive from Google as a MBOX. It was then a question of adding an add on to Thunderbird to read the MBOX file and now all her emails are back in Thunderbird. All she has to do now is go through them and make new subfolders etc. Downside is that all her deleted emails have arrived too. A small price to pay for not having lost them! I just hope she has learnt her lesson and will read what she is about to do rather than just clicking on things.