Iphone has restarted itself and is now reported as lost / stolen. icloud wont let me switch it back on

Your iPhone is reported lost or stolen by itself?

Was it a new iPhone or have you bought it second hand? If you bought it second hand the chances are that the previous owner has put it in to lost mode.

If your iPhone miraculously did this by itself try this to turn off the lost mode

1. In Find Devices on iCloud.com, select the device in the All Devices list on the left.
2. Click Lost Mode, click Stop Lost Mode, then click Stop Lost Mode again.
3. You can also turn off Lost Mode by entering your passcode on the device. If you turned on Stolen Device Protection on your iPhone, you may need to use Face ID or Touch ID.

ReneMallett wrote:

I have the email from them

Really ?

My Apple ID

Is the device listed as a Device In your User Account with Apple ?

In my case have two Apple Mac Minis - 1 MBA, iPhone and 1 iWatch all listed

If your iPhone is listed, then, no one has Removed the device from your ownership

It sounds like someone might have access to your AppleID (typically via compromised credentials).

See:

If you think your Apple ID has been compromised - Apple Support

The email is not from Apple.

Again, I strongly suspect a compromised AppleID …

… and also suspect that the eMail you received was actually from the criminals masquerading as Apple.

Hopefully, my skepticism is misplaced in this instance.

Re: “… seems apple support has put my phone as lost / stolen …”

That’s NOT an action Apple would normally perform.