It is often suggested before making any major changes to your site to make a backup.
If you have cPanel you can go to cPanel > backups > download or generate a full website backup
Note your host will usually have to restore these backups.
Alternatively, you can manage and administer your own backups with a tool like
Akeeba Backup.
Following the instructions from Akeeba Backup, there are four stages to this process:
- Installing Akeeba Backup
- Making A Backup
- Downloading Archives
- Restoring Your Backup
You can watch these steps here -
https://www.akeebabackup.com/videos.html