How can I get my old emails from a POP email server?

I reformatted my computer and so have lost all my mails in the inbox of outlook email program, how can I pull my old emails i recieved before like 2weeks before from my provider's server

How can I get my old emails from a POP email server?
That's a question you really have to put to your email provider. If your setting in the email client program was NOT to save a copy of the message on the server, those messages will likely already have been erased from their servers and cannot be retrieved.