This is one of the most common issues on WordPress. Occurs mainly after
- WordPress Website Server Migration
- WordPress Website Domain Change
- WordPress Website Theme change
Issue:
You are getting 404 on all other pages apart from Homepage
The Fix:
Fix the Permalinks.
Login to your Website Dashboard

yourwebsite/wp-admin
login with admin username and password
Click on Settings

Click on Permalink

Under Custom Settings
Select Plain Option, then Click Save
Then Click the Post name option then Click Save

This regenerates your htaccess file and thereby fixing the 404 error on other pages.
Your Website should now work perfectly.
This post is sponsored by Olitt.com – The Home of Free Websites & Online Stores