Is there any way to block all non-friends on facebook?
Well, I know of a profile which can't be viewed by any non-friends at all? Why is it behaving that way? Is it because it is about to deleted by facebook?
Ah, ok. AFAIK, the only way to make a page show "Page not found" is to deactivate the account entirely. Check out the Help article on how to deactivate your account: https://www.facebook.com/help/359046244166395/
Watch out - this will remove the access to someone's profile for EVERYONE, not just non-friends. If you are looking to block ONLY non-friends, then controlling your privacy settings is a much better idea. Deactivating it will prevent the page from showing up on both friended and non-friended people.
You can deactivate/reactivate your Facebook profile whenever you like:
I'm not sure what you're asking here, but if it is related to Facebook's Privacy settings, you can read more about it here: https://www.facebook.com/help/privacy
Check out the "Controlling Who Can Find You" section. It provides options on turning on (or off) the ability for non-friends to find and/or message you on Facebook.