The Nigerian was part of the squad detained for several hours at a Libyan airport ahead of an eventually forfeited African Cup of Nations qualifier.
Nigerian players and staff were left without food, water and phone service for half a day.
Cooper said: "He's fine. He's back with us, safe and well. We were in close contact with him throughout the situation they found themselves in. He kept us updated.
"There were Wi-Fi issues so it wasn't as often as we would have liked. He was back with us soon after and has trained. He's in a safe place and that includes the mental side of it too.
"He trained really well yesterday which was pleasing to see. Maybe he needed that release. He's fine. We've checked with him in every way we can. He'll be ready like everybody else."