Hey there Bendy83,
Thanks for reaching out to the Apple Support Communities.
To get started, the first step would be to find out if the backup for that device is still available in iCloud. For help with locating previous backups, check out this link here: Locate backups of your iPhone, iPad, and iPod touch - Apple Support
Find and manage backups stored in iCloud
If you use iCloud Backup, you won't find a list of your backups on iCloud.com. Here's how to find your iCloud backups on your iOS or iPadOS device, Mac, or PC.
On your iPhone, iPad, or iPod touch:
1. Go to Settings > [your name] > iCloud.
2. Tap Manage Account Storage, then tap Backups.
3. Tap a backup to see more details about it, choose which information to back up, or delete the backup.
On a Mac with macOS Catalina or later:
1. Choose Apple menu > System Preferences.
2. Click Apple ID.
3. Click iCloud.
4. Click Manage.
5. Select Backups.
On a Mac with macOS Mojave or earlier:
1. Choose Apple menu > System Preferences.
2. Click iCloud.
3. Click Manage.
4. Select Backups.
On your PC:
1. Open iCloud for Windows
2. Click Storage.
3. Select Backup.
If you're able to confirm that the backup is still available, learn how to restore previous backups with the steps in this next link here: Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
We do want to make you aware that if the backup was created on a device running a later iOS version, the iPhone would need to be updated to the same iOS version or later to restore the backup.
Let us know if the information above was able to help.
Have a great day!