If this is only a temporary situation and you will get a replacement computer very soon, maybe you would be content to just use webmail in the meantime.

Is there any way you can get some files off the broken computer and copy them to a flash drive or something? If so, you could copy your Thunderbird profile from that machine to the Dell. This would be the best solution, as you won't risk losing any emails.

If not, you can install Thunderbird on the old Dell, and create a new account that will connect to your email service. You will then be able to retrieve any mail currently on that mail server. Further advice depends on the answer to this question:

Was the broken computer connected to the mail server via IMAP or POP3? Or do you not know? Once we know that, we can suggest the next steps toward recovery.

The reason that answer is important is that if it was IMAP, copies of your old mail and folders will still be on the server. If it was POP3, the old mail only exists on your broken computer and will permanently lost if you can't get it off the old hard disk.

My dell has nothing it was reset. The broken computer has files and I am able to copy to a flash drive. Email is IMAP. What directories do I need to look for to get the data copied to the Dell? Thank you so much!

OK, good! You have a good chance of recovering everything.

On the broken computer, look in the folder:

    C:\Users\<your Windows user name>\AppData\Roaming\Thunderbird\Profiles

- There you'll see one or more sub-folders, one of which is your profile. If you're not sure which one it is, look inside and see which one has the most recent files. Make a note of the name of that folder.

- Copy that folder to your flash drive. It can be quite large, so make sure your flash drive has enough room.

- Install Thunderbird to the Dell. It would be best if you can install the same version as on the broken computer.

- Copy your profile folder from the flash drive to the equivalent location on the Dell.

- On the Dell, press <Windows key>+R to bring up the Run dialog box. In the text box type:

thunderbird -profilemanager or thunderbird -p

to start Thunderbird's Profile Manager.

- Click the Create Profile... button, then Next. Give the new profile any name you like. Then click the "Choose Folder..." button.

- You will now see the folder you copied over from the broken computer. Select that folder and choose the "Select Folder" button. You will then be returned to the Create Profile Wizard dialog box. Click the Finish button. You will be returned to the Profile Manager.

- Make sure your newly-created profile is selected and click the Start Thunderbird button. You may want to check the "Use selected profile without asking at startup" option.

If everything has gone according to plan, you will now see Thunderbird much as you're used to seeing it on the broken computer.

Here's Mozilla's official instructions for the procedure we just did. Their method is somewhat different than mine. but but the end result is the same:

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