Restores are usually urgent, so know the routes before you need them.
FROM JETBACKUP
Available from WHM, or from within the client's cPanel where your plan includes it. Choose File Backups, Database Backups or Full Backups, select the date, and restore.
For a site rollback, restore files and database from the SAME date. Mixing dates leaves the site inconsistent in ways that are hard to diagnose.
FROM A CPANEL ARCHIVE
WHM > Backup > Restore a Full Backup, or restore the account through the Transfers tool. If you hold only a partial backup, upload files through File Manager and import the database through phpMyAdmin.
FROM A PLUGIN BACKUP
Restore from within the application, using the plugin that created it.
BEFORE RESTORING
Take a copy of the current state. It may hold orders, form submissions or content created since the backup, all of which the restore overwrites permanently.
Tell the client what will be lost. Anything added since the backup date is gone unless exported first.
AFTERWARDS
Clear caches, re-save permalinks, test the site and admin login, confirm email works, and check cron jobs survived.