My iPhone (8 )Home Screen has disappeared. It was normal this morning; now I get a very different screen. How do I get MY Home Sceen back? Hard re-boot doesn't work.

Probably you have reset the Home Screen Layout as shown below.

Reset the Home Screen and apps to their original layout

1. Go to Settings > General > Transfer or Reset iPhone.
2. Tap Reset, tap Reset Home Screen Layout, then tap Reset Home Screen. Any folders you've created are removed, and apps you've downloaded are arranged alphabetically after apps that came with your iPhone.

Move apps and widgets on the Home Screen on iPhone

If you feel an unauthorized person/app is remotely using, controlling or monitoring your device, then that is possible only if you have done one or more of the following Don'ts...

1. Don't hand over an iPhone to kids or to a stranger without Enabling Guided Access
2. Don't share Apple IDs
3. Don't Jailbreak
4. Don't share sensitive information pertaining to your device
5. Don't give in to Phishing
6. Don't plug in your device in Airports and Public places through third-party cables and trust the device. Beware of Juice Jacking. (Especially in India)
7. Don't leave your iPhone unlocked and unattended in public places like offices, schools, malls, etc.

If one of the above is true then quickly change the Apple ID Password and Return iPhone settings to their defaults.

If the Home Screen Layout is reset, the only way to restore the original layout is by recovering from a backup; there is no alternative method available.

If you have a backup then you can restore from it. Hope you are aware of the restoring process which will wipe out everything on your device with that of the backup. 

If you are 100% sure that the backup that you are restoring has the data that you are looking for and are ready to wipe out your current data. Else take a current backup and archive it. Then restore.

How to create Multiple Backups for the same device.

1. On iTunes Click on Manage Backups
2. Right Click on a Backup and Click Archive
3. Click Backup Now.
4. You will see a fresh backup will get created See the GIF below