404: Page not Found

Website Building
#1

I am creating my website, as i am customizing it, before i could click menu or create menu, it displays ‘404: Page not found, the page could not be display’. What is responsible for this? please help.
Thank you very much.

#2

Where do you see this sorry?

#3

image
image.png1360×768 71.9 KB

Look at the screen shot. I am to customize it when this happens.

#4

Try settings > permalinks > default/plain

#5

image
image.png1360×768 88.8 KB

I have checked the permalink settings, I can not find anything wrong.
See the screen capture.

Thanks

#6

Hit plain see what happens?