I had to uninstall the Mozilla email program.

Unless you deliberately choose the option to delete the profile upon uninstalling Thunderbird, all your mail would still be in the profile.

I lost thousands of emails in folders.

It isn't clear at all why that should be the case based on the limited information you provided. You'd need to provide more detailed information about what you did and what actually happened.

I was traveling in Mexico. Microsoft ran an update. After the update the computer completely froze. No key broad nothing worked. We had the uninstall all programs and reset set the computer. Now we reinstalled the Mozilla email program but the folders and emails never came back?

... and reset set the computer.

Not exactly sure what you mean with reset. If this is to restore your PC to factory settings, it did also delete all of your personal files and apps. That means your profile is gone, and you'd need to restore a recent backup to get back your mail. This assumes you actually did create a backup.