We don't know what they did. If this is an IMAP account, my first suggestion is to rightclick the account in folder pane and click 'subscribe' to see if the missing folders are simply unticked. I also suggest logging on to the online account as that will definitely confirm the existence of the message folders.

This is a pop3 email account

You paid professional support folks to loose your mail and now you are asking a volunteers community to pick up where the people you paid left off and actually fix the problem.

I feel you should get best buy to at least refund your money as I have never heard of a fix that requires the account to be removed and added again. %o be honest I am tired of trying to help folk after they screw up their job and collect their pay for it.

It is something that comes up in this forum frequently from people that have either paid to have it done or followed faulty advice from their mail provider. One of the worst for that being Yahoo. They like best buy start every support with remove and add it again loose folks data throw their hands in the air and you pay for the service.

Your data is probably still on your computer because it does not sound like the folk you paid had sufficient skill to actually remove the data files, but there is an option to remove data when an account is removed, if they selected that then it is all over. We might be lucky and Thunderbird has lost the connection to the data when the account was removed. Folders usually hang off the account, remove the account and those folders no longer have a nail to hang on.

So try this.

Goto the help menu Select troubleshooting information select the open profile button in the troubleshooting information. It is in the first block of data buy my be just off the bottom of your screen so you might have to scroll. When the profile opens in the file manger /Explorer open the mail folder that will be shown What folders are in that pop folder? I would expect the to be Local folders and more than one pop.comcast.net folder. But I will leave that for you to report back when is actually there. in the way of folders.

Okay. I used AI to try to help me. It identified that the Geek Squad turned my email account from a POP 3 to an IMap. It also showed me where the missing emails are, but I can’t access them. When I try to access a new version of TBird, it keeps directing me to the old version. Does anyone here understand what is happening and can simplify the process?

You do not need another version of Thunderbird if you already have one installed. That just makes things worse. If you will share here where the POP messages are, we may be able to assist in advising how to salvage them.