[AnimalMuppet]

Do you want to continue being a manager? Do you want to continue to be a developer? Both? Are you unhappy because you feel rejected or unappreciated? Or do you really miss the work?

They could assume that you want to be a developer and not a manager. They may be intentionally sidelining you, and think that they're doing you a favor. The only way you can fix that is with communication.

Or, they may currently need you as a developer more than they need you as a manager. If it's temporary, you can choose to ride it out, making it clear to them that you want back into management when possible.

TL;DR: You have to talk to them to find out what they're thinking, and why they're doing what they're doing. Don't guess. Ask.