Pls help–can’t send or receive emails but it opens and I can open existing emails

My family and business rely on email. 

Just today, it stopped sending or receiving, and returns incoming emails.

I paid to resubscribe to the Ad-Free option, which ran out a while ago I think, although no ads started appearing.

I read about Reinstalling Windows Live Mail, but my Windows Eight has no start button.

Also, I have thousands of saved emails and folders. Exporting them will be a dangerous nightmare I am sure.

There must be a thoughtful step by step trouble shoot for this.

Help!!!

To clarify, I never used Outlook when it was something else.  Hard to believe they used the name of another product for the email product, but I thought I would mention.