How to fix your php installation appears to be missing the mysql extension?
In this article we are going to solve
your php installation appears to be missing the mysql extension which is required by wordpress.
This issue is commonly occurs due to mysql extension has been disabled from your cpanel. So to solve this issue we have to:
1. login to your cpanel.

2. look for the section “select php version”

3. Enable “nd_mysqli” and “mysqlnd” from the extensions tab and save changes

If this didn’t solve your issue you will have to contact your website hosting provider and they will login to your cpanel and reinstall mysql extensions.