A friend changed there number how can I get there new number from there old number

You can't.
Why not just ask them for their new number...

Find new number from old number for free

Not possible, and not even by paying for it.

Most number changing is done by people who don't want to be called.

Call the old number. If they want you to have it, it will give you the new number. Otherwise you will not find.

If this is truly a friend, you should have other ways of contacting them. If not, maybe you are why they changed the number. There are laws against stalking.