First of all I am so sorry you are feeling rubbish right now. You're not alone - much less than you feel. Many of us are feeling some of the things you are describing - some or all of the time, more or less depending on the day! THis is a tough season and it is many things but it definitely ISN'T normal - and so its not surprising that a lot of us do not feel normal either! Be reassured that the things you are feeling are totally the kind of things we might expect - it just shows us you are human (yey!).
So - two things ... first of all, this season has through with it a whole load of loss and grief. Not everyone has had grief like bereavement - people who have died - but we've all lost stuff - things we expected to be doing, normal bits of life, people we love who we can't hug or hang out with ... and that stuff is hard in the moment but also hard because it makes our brains question some of the things we always assumed about the world, who or what we could depend on. And your mind needs time and space to think that stuff through - and it can't do that when daily life is carrying on - so sometimes we feel flat and like hiding away because our minds want us to have time to ourselves to try to figure this stuff out.
The second thing is though that right now we're all really tired and fed up - because this has gone on for A LONG TIME!! Seriously! It has!! And when you are tired your mind doesn't have the energy for things like enjoying stuff or having fun - everything in it just tells you to go to bed, rest, refuel... So you feel like your get up and go ... well, got up and went! But it isn't permanent - you just need a break. We all do!
So what do you do? Ok, three tings to think about ...
The first is how can you get some rest? The holidays are coming up and this year more than any we do need to get some time out. I know you may have school work to do but if you can make some times where you deliberately don't think about it, and plan when you'll do it so you can properly do that - even put it away in a cupboard or something or get it done early in the hols so then you can relax - whatever it takes. You might even need some days where you get away from the usual everyday stuff - even mates and friendship stuff - because at your age that can be hard work too even with your best mates. Take some time out, don't feel bad about needing it - rest, sleep, chill - anything that is about relaxing is good stuff to do!
Secondly, think about how you can find some spaces where you can talk a bit or ponder a bit all the stuff in your head right now. That might be alone time - just listening to music or doing something like journaling or craft or stuff that is about good time just on your own with your thoughts. But it's also about time with people you can trust, where you can chat, bounce around your thoughts, compare notes on the stuff you are fed up with right now - space where no one tells you to be more positive or to stop moaning! And it might be that you'd find it helpful to have a more formal space where you can do this - someone you can talk to who is focused on helping you think stuff through - that could be something like counseling or someone professional to help you, or someone like a youth worker or church leader, or just another adult you know well like an aunt or Godparent or one of your folks.
Thirdly - think about experimenting with fun stuff. Because the thing is when you are overwhelmed like this you enjoy different things. Stuff you usually like might feel a bit much - and things you wouldn't usually go for actually are kinda good for you right now. So try some new stuff. Think about what connects you with other people - where do you get to hang out with folk? Think about things that get you out of the house - walking or getting your bike out, or doing treasure hunts or whatever. Think about things you normally wouldn't enjoy - craft stuff or reading or movies or sports or gaming ... be analytical and give lots of stuff a go - try not to rule things out just because you think its not for you - in this season different things might be helpful to normal so think like a researcher and find out what works.
And remember - if you ever need to talk or things feel really overwhelming, there are places you can go to connect with someone online who can help you - so don't ever struggle with intense stuff on your own - check out this article for some links.
Most of all though, don't feel guilty and don't feel afraid by what you are feeling. This stuff is a normal reaction to a NOT NORMAL situation! And things will improve - the trick is to find ways to recharge and get through until we can get back to something more like normal life.