Without knowing details, the possibility is remote. However, depending on how it was done, it's always worth a look. The default profile folder would be a c:\users\<userid>\appdata\roaming\thunderbird\profiles.

Unfortunately, I connected remotely and there is only one folder. There were two profiles for two different accounts and one remains. Unfortunately, it doesn't seem to be there anymore...Unless I'm looking for something wrong?

But I checked the path you are talking about carefully and there is only one folder there, which probably contains only the account that is left and the deleted one is not there.

Because I understand that if there were two different accounts, there should be two different folders?

A profile can contain multiple accounts. At this point in your concern, I would make no assumptions. If there is just one account shown, check it anyway. And there may still be message folders in the Local Folders folder.

Yesterday I ran a system restore from day 23, which is a few days before deleting my account. Unfortunately, after logging in again to the mailbox, there are still no messages. However, such folders appeared in my thunderbird profile - app data roaming