Backups: what a nightly copy does and does not cover

Every plan keeps a copy of your files, databases and mailboxes from each of the last 30 nights (sample).
That covers a broken update, a deleted page or a hacked plugin: we restore the night before it happened. It does not cover orders placed since the last backup, so tell us the time of the problem and we can restore only the files.
Before a big change, make a staging copy from your account and try it there first.