do you see any sort of error?

When I try to print a pop up appears as if I want to save a document. Immediately thereafter a message appears: something went wrong with printing

You obviously have a print to file installed in your operating system. Use thunderbirds config editor to delete the preference under printer.print and force the selection of another printer.

https://support.mozilla.org/en-US/kb/config-editor

Dear Matt, Thanks for your help. Being a layman, I am reluctant to follow your advice without assistance of a specialist. To prevent a misunderstanding I will try to summarize what happened. 1) After using Thunderbird for a long time and having no problem at all to print emails, suddenly I could not print emails anymore. 2) I do not have the same problem with Firefox nor with any other program. 3) I have only one printer. 4) After the problem occurred System recovery was used- for another reason - to start with a clean slate. Thunderbird was reinstalled: but still I could not print emails. When I use windows live mail I can print emails. Does this change your advice? Thanks in advance.

Nope. Nothing you say there is reason not to follow Matt's advice. Thunderbird thinks it knows which printer to use but it has it wrong, so removing the pre-set printer from Thunderbird's settings will prompt it to ask you again. Since Thunderbird has its own settings, what happens in other programs isn't very helpful.

Print preview in Thunderbird may give you a prompt. Try that too.

These questions puzzle me, because on all of the different computers where I have Thunderbird installed, I always get asked which printer to use. I don't know how to get to where you are at right now.

I am in your boat Zenos, I can not get to to "just print" I always get a select printer Dialog. But what can I say, I print about 3 emails a year so trying to answer these questions is about all the exercise my print function gets..