You should periodically create a backup copy of your website.
You could do this using the Backup utility included with the Hosting Control Panel provided by your hosting provider.
Or alternatively install and use a Third Party Joomla! Extension.
For example: Akeeba Backup PRO.
About this Article
Akeeba Backup PRO offers lots of options, most of which should be avoided until you have read the relevant section of the developer's extensive User Guide.
Fortunately, creating a Backup archive is almost intuitive.
But there are a few settings tweaks you could usefully make before creating your first Backup archive.
FIRST, purchase the Akeeba Backup PRO subscription.
Some Useful Tweaks
Restoring an Archive created using Akeeba Backup
Be aware before starting to use Akeeba Backup that to restore a website from an archive created using it requires the use of an extension called KICKSTART.
This extension is provided FREE by the developer.