Show me a moody teenager and I'll show you someone who won't adapt to change, much less embrace change or accept that a change has happened.
Before we proceed, check out the following video:
After you watch it and if you have a moody teenager who doesn't want your advice, show it to him or her and ask them if they can relate to it. And if so, ask them to explain. And if not, ask them to tell you what's true for them when you try to help them by giving them advice.
(BTW, if you noticed the grammatical errors in the video and they bothered you significantly, the greater the likelihood from your teenager's POV that you focus more on what he or she is doing wrong or failing to do, instead of what they are doing right -- which is no excuse for my making those grammatical errors.)
Very often, your teenager's moodiness is tied to something in their world that has changed and their continuing to use an approach that no longer works. (Teenage) insanity is doing the same thing over and over again, but expecting different results.
Next -- and if your teenager agrees with the video but is in an even darker place -- read this: article: "What Your Teenager Wants You to Know, But Won't Tell You" (I'm warning you, that it's very dark) and then tell them you'd like to apologize to them (even if you have nothing that you've done wrong) following the five steps in: "Why apologize when you're not sorry." Do this because most people are defenseless against a genuine apology and this may help your teenager to lower their guard and let you in.
If they agree to let you fix what you've been doing wrong, show them the "What Your Teenager Wants You to Know, But Won't Tell You" article and go over it line by line, watch the videos together and ask them what they read and see that they can relate to.
Then tell your teenager that you need their help going forward and ask them to tell you what you need to start doing and stop doing to help them feel less alone in the hellish place they have been in.
Finally, ask them to please look you in the eye and then say to them: "I really am truly sorry that I never knew how bad it was for you and didn't want to know and how that left you alone in hell for long periods of time and with your permission and help, we and I are going to fix that."
BTW there is a possibility that the reason you haven't connected to your teenager in their pain is because no one ever did that for you and so you can't give what you didn't receive.
Furthermore, if you're a high achiever and not very happy yourself, there's a good chance that achievement and accomplishment has never fully taken away the pain you felt at being alone during some of the darker periods of your life and that you may be suffering from the Syndrome of Disavowed Yearning.