If they scanned and found chip, they tried to contact you. The animals are also on a hold period, longer if they are chipped. If you didn't look hard enough for your dog and it was adopted out after all those attempts to find and contact you, that is on you. Once adopted, you will not be getting your dog back. Sorry
I don't work at the shelter, you'd have to call them. However, that's the whole point of the microchip. If you registered your chip with the company and your vet has records of it, that is proof that it's your dog.
I'm sure they have some sort of record which would get your dog back. Either way, you can always take them to court.
Thanks! Your answer is awaiting moderation.