I am unable to track or block my lost iPhone

FYI: An iPhone is very securely locked by it’s passcode; there is no “blocking” provided thru Apple.

You may “Mark as Lost” as a recovery aid.

Your carrier may blacklist the phone when you report it as stolen.

Thieves will generally take active measures to prevent a stolen phone from being located w/ FindMy.

See:

If your iPhone or iPad is lost or stolen - Apple Support

If you are seeing "No Devices" then:

• Find My was not on
• You are signed into a different iCloud account that what was used for your iPhone
• Someone knows your Password and was able to remove the device
• If you responded to an email/message claiming to provide the location of your device, then it was a scam and the thief took over control of your iPhone by using the information you gave them.

• What happens when you try?
• Did you have Find My turned on?
• What iPhone model? Newer ones can still track even if turned off.

Just wanna find out how can I trace it if the device is off

mpilwenhle49 wrote:

Just wanna find out how can I trace it if the device is off

If it's off, you can't.

FindMy is the only Apple-provided means to locate any device.