Was ist der Unterschied zwischen this pen has not used by anyone yet und this pen has never been used by anyone ?Du kannst auch einfach Beispielsätze geben.

They can mean the same thing, but I would also use them in different contexts.

"This pen has not used by anyone yet" implies it could be used by someone in the future. For instance, "This pen has not been used by anyone yet so you should be able to write with it for a long time."

Now, imagine you're in a museum and there's a gold pen from 100 years ago. Someone could say, "This pen has never been used by anyone." In this case, it would be strange to say "yet" because that would suggest someone could start using the pen. But it's not meant to be used. It's a museum display. So, "never been used" is best.