My ex husband abandoned NY sin in Portland or. And they sent him bk to Utah now I need to find him.

For what purppose... Don't you have visitation rights established? Don't you know where he lives. If you don't know where they are... how do you know the information he was abandoned is correct... and that he was sent back to Utah?

Are you saying that your ex husband abandoned your son in Portland, Oregon? And that someone sent the son to Utah? Who sent your son to Utah?

I assume your son is a minor, correct? Which of you, you or your ex, has the right to physical custody of your son?

Which one of you has custody? What state are you in? You said they sent him back to Utah. Is that where your son lives with either you or his father?

As you can see the way you worded your post leaves us with question that need answering before we can advise you.

You said; "abandoned NY sin". Did you mean abandoned my son or what?
You said; "they sent him bk to Utah". Who is they? Where in Utah? Why Utah?

Also where are you located? Why was your son with his father? How old is your son? How long was he with his father? Are there any court orders for custody and visitation?

Please return and answer these questions so we can help.

... Who is they? Where in Utah? Why Utah?...

I don't know that we need to know where. But who "they" are is the important question. And I don't understand why OP doesn't simply as them.