I'm having a similar problem. I made the mistake of writing my content in Word and then copy and pasting to my web page... for some reason there was a line all the way down the length of the page and there was nothing I could do to get rid of it (I even re-typed the whole thing from scratch and when I saved it and viewed the website again it was still there).

So I deleted the page, created a new one and retyped it from scratch again. Same thing. Same line. No other page has it... just this one.

So I deleted it again and created a new one and retyped it all again. But now when I view the website and click on the page it says "page cannot be found". I can click on the page in the dashboard and the content is there. I've checked under menus and it's there in the correct place. I just cannot find it on the website (the heading it there but nothing when I click on it).

The website is http://howtogetthatjob.org and the pesky page is called Cover Letter under The Application tab. Any help would be greatly appreciated!

Make sure you go back to your menu set up in appearances and add the sub page to the menu, then place it under the parent page with an indent. Your menu page should then look something like the attached pic

I have a helpful video on menus if you'd like to check it out:
https://youtu.be/wVkyfnyRx2Y