Q: My iPhone is stolen, how can I block it if I can't find it anymore?

Log into iCloud.com. You don't need an apple device.

Now we are out of my comfort zone! Are you on a PC? You may need to download icloud for windows. Check this link: Download iCloud for Windows - Apple Support

Or try going directly to find my iphone with this URL: icloud.com/find

I totally understand, and someone who is more PC will hopefully stop by soon! I really don't get why you don't see it at iCloud.com, but hopefully you will at iCloud.com/find. You are sure you have set up Find my iPhone?

For the protection to work you have to have Find iPhone enabled - it does not matter if you log in from a Mac or PC or use Safari or Chrome - you see the same things

See the picture - this is the default view - if Find iPhone is not showing then you have probably not enabled it

I'm so sorry if it's not enabled. Next steps are probably to deactivate your phone with your service provider and then start visiting the websites of the apps that your phone is logged into. Many places will let you log out everywhere, including the phone. My sister had to do this recently, and she was very happy that she could remote log out from Gmail!

I would log out of iCloud and change my password at the very least -

Everything I've read suggests no, but here's a link to Apple Support: https://www.apple.com/support/contact/

There's no action to persuade Apple to take.

If the horse is gone and 3 fields away, you can't lock the barn door now.

If FMIP was not enabled, there is no way to enable it now. By anybody, including Apple.

Sorry.