I phone locked to owner

The phone will not be able to be used. The only way to buy a used iPhone and be sure that it is not stolen is to physically verify that it starts up to the "Hello" screen. This cannot be done over the internet, so the simple answer is to learn from the mistake and don't do it again. A stolen iPhone has no value.

If you own an iPhone, you would want the same protections to keep you personal data safe and also to be able to lock your phone if it is stolen. To sell or give away an iPhone, you would then need to follow this article:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

You told us.....

It says " i phone locked to owner "

This phone shows the "hello" screen

Which one of these statements is correct?

Return the phone for a refund. You will not be able to use the phone unless you can find the original owner and get them to unlock the phone.

Please return the phone for a refund.

The phone is useless unless the original owner can be located to unlock the phone. No one else can unlock the phone.