Is this a pop or IMAP account?

POP. Thank you. Also cannot access Incoming Server settings. Here is screen shot of page:

Are you able to show us the Account Settings page please? What happens if you click on "View settings for this account"?

We can't see the alleged POP account, let alone its Inbox etc. As far as it appears here, there is no email account set up.

What we can see is your Local Folders "special account" and Local Folders doesn't have any server settings.

Has this missing account ever worked? If so, when did it stop working? Was it connected with any event such as an update?

Here is screen shot. Have used this account for many years and worked fine until a couple weeks ago. All files disappeared except for Local Folders down as shown. View settings only gives outbound.

Thunderbird has lost that POP account.

Your mail stores are probably still there. I'd look in the profile, identify the mail stores under "Mail", then if happy that it's there, re-install the account, close Thunderbird, and then

• copy the old mail store (Inbox etc) over the newly-created folders set up when you reinstalled this account, or
• just copy the old mail store files into Local Folders.

Yes they are there - I have been accessing through Yahoo. Where is profile? Sorry this is stretching my expertise.