This guide will explain how to check WordPress core files, if these have been changed it can prevent a site working and can also point to a site being compromised with malware
TL;DR WordPress core files can be checked via cPanel > WordPress Toolkit > Check WordPress Integrity > Verify Checksums
Requirements
To complete this will require having a cPanel account with a WordPress site installed and the site has been added into WordPress Toolkit, to do this here is a guide for How To Scan & Add a Site into cPanel’s WordPress Toolkit
How to check WordPress core files using WordPress Toolkit
Step-by-Step Guide
1/ Search for WordPress Toolkit
In cPanel search for ‘WordPress Toolkit’ in the top right search bar and click on WordPress Toolkit from the search results
2/ Click Check WordPress Integrity
Inside the WordPress Toolkit go to the Dashboard tab and click on Check WordPress Integrity
3/ Verify Checksums
Click on Verify Checksums, this will compare the site files to the WordPress Core default files
4/ Checksum Complete
WordPress Toolkit will confirm if the WordPress core files are the same as the default WordPress version
Video Tutorial
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Summary
This check will confirm if any changes have been made to the WordPress Core files, if this reports changes have been made, the WordPress core files can be re-installed using the following guide: How To Reinstall WordPress Core Files using WordPress Toolkit