Well,
Did you check if everything is up to date, WP, theme, Plugins….
Paste the content of the system info box found in the help page here so we can check that.
Did you check if you have any posts defined, can you see the individual post page if you click view from the Post editing page
If you do, have you tried creating a new test page and select the “page with posts” template for it and save, to see if that page shows the posts