bearded dragon help...

Courtney🤘🏻 • I just want to cuddle my boyfriend and pet my cat. 👫🐱
My boyfriend for a bearded dragon a couple months back, this was the first one he's ever had. 
Well last week ish, his mom noticed that the dragons beard was turning black. No one did anything about it, well today she woke up and the dragon wasn't moving, and it doesn't look like he's breathing. 
I read online it could be he's hibernating. 
Could anyone help me with this? 
The dragons about 1 1/2 to 2 years old.