Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
If you are getting error “Your PHP installation appears to be missing the MySQL extension which is required by WordPress”, This could be because your PHP version is not compatible with your current wordpress version. HOW YOU CAN FIX THIS ISSUE Below are the steps you can follow to fix this issue. Take the backup of your files and wordpress database. Change your current PHP version to 5.6 or lower. Update your wordpress, and all plugins which are outdated. Update your PHP version back to latest version. You will see that everything is working fine.