How to solve 404 Error on website?

How to solve 404 Error on website?

Create them manually in your .htaccess or your NGINX server config. ...
Create them with a redirect plugin. ...
Create them with our Yoast SEO Premium plugin

1. Retry the web page by pressing F5, clicking/tapping the refresh/reload button, or trying the URL from the address bar again. ...
2. Check for errors in the URL. ...
3. Move up one directory level at a time in the URL until you find something.

Hi,
your are checking for URL there showing 404 error ie page not pound
solve this problem , you want redirect old URL to New URL

404 Error is a HTTP standard response code Indicate that a server unable to response the client request. Due to Broken or Dead links, Server returns 404 Error. Analyze your site whether it have any dead or broken links. In cause if it has, correct the link and use Robot.txt to avoid that broken link listing in SERP.

Steps:
Go to google webmasters and go to the tab named as google index and you will find a option as Remove URLS where you can upload a link which you does not want google to crawl.

you should redirect broken links at 404 page