Let's not get into the 'whys' in this article. Because whatever it was that made your teenager depressed, the journey down takes us all to the same place: a feeling of utter worthlessness combined with a black cloud that wants nothing except to make your day as long and as miserable as possible.
So let's instead focus on what you can do to help your teenager who won't talk to you, or come out of their room or refuses to join you for the family meal.
Yes, you're worried and you have a good reason to be worried. Don't let others sway you with It's just a phase. Teenagers do go through a hormonally driven, emotional upheaval and can seem ratty and illogical at times. However, that's part of the territory.
A happy teenager - if there is such a thing - is one who is sometimes down and occasionally depressed but not for days and weeks on end. A depressed teenager hasn't got the height to see life's full landscape and to know that there is light at the end of the tunnel. To them, depression can seem like a one way street which winds up in a dead end.
Communication is the key. The problem is that teenagers don't want to communicate with their parents, they want to talk to their friends. But, a depressed teenager needs the guidance of at least one caring and astute adult and a parent is the best person for the job - better than any doctor, psychiatrist or counsellor.
So, what do you communicate about? Them! And their feelings and thoughts. However, they won't open up straight away so you need a plan.
Teenagers talk best when they're distracted by doing something else - with you - the parent. Like a walk, doing the washing up, driving, any type of relaxed travel, going to do something fun, gardening, being on holiday etc. It's a two pronged approach here - it's the being distracted that stops them brooding and it's being with you - the parent that shows them they're worth your time. Doing things together increases their self esteem and they feel valued.
The more time you invest, the more they'll open up. It might be difficult to prise your teenager out of the bedroom to kick this into touch so you'll have to be creative.
Once they begin to talk, the key is to listen. It's tempting to want to jump in with solutions to their problem friends, teachers and social media peer group. It's easy for you to see what you would do to change things. But you're not walking in their shoes and life is very different for today's teenager than it was for us.
So when they talk, listen to their words. And then repeat back what they say. Word for word if possible. You can pre-empt it with: "just so I've got this absolutely right, what you said was...." (and then repeat it) What happens is the teenager feels, maybe for the first time, that you have really listened and heard what he/she is saying. They may give you an incredulous look. They could 'diss' you for being so 'weird'. But keep going; you may have to build the trust slowly and it could take a while but this is the most direct way in to their hearts.
Don't offer any advice until the teenager asks for it. Then when you have gained their trust you can - gently - step in with guidance and suggested options.
Having someone hear your problem without judgement is one of the most powerful gifts you can receive. And to offer this to your teenager will help to build bridges back to a solid relationship. This work will also foster the beginning of your future, and lifelong, friendship. They may, in the future, talk about this life affirming time you spent with them and mark it as a turning point.