I fully sympathise with your situation. I have been there and it's not easy. Here are some tips that have helped me:
1. Be compassionate to yourself.
When you have low motivation, it's important to be kind and compassionate to yourself, and ease yourself gently into getting back to work. Like IAT said, an hour a day is a good goal. You may have days where you can manage this, and you may have days where you can't. Don't beat yourself up about it. By overly criticising yourself, you enter a cycle of guilt that will only demoralise you and make it harder to find motivation. If you end up getting annoyed at yourself and berating yourself internally, try and find another, more compassionate voice to challenge those thoughts.
Let's say you get 15 minutes of work done. Instead of thinking, "I only did 15 minutes, that's not enough, why am I so useless?", tell yourself, "that's awesome, Iszie, you're doing amazing, keep it up!" Talk to yourself like you would a close friend. It might feel silly, especially if you're used to being hard on yourself, but it will help you enter a better place mentally, and be in a better state to work effectively.
I've found it helps to consider a "zero work base level" when you're struggling to get any work done. Instead of telling yourself you need to do so many hours of work in a day, set the expectation of doing no work, and any amount of work you do "above" this level is something good you have achieved.
2. Work because you choose to.
Don't let your school stress you out unnecessarily. You do not have to work every day this week. In fact, it might help for you to take a day or two of complete break, where you don't think about work at all. It sounds like you are feeling burnt out and could do with time away from schoolwork to let go of the things stressing you out, and return to it with a clearer head and more energy. Also, try to rethink why you are revising. Rather than seeing it as something your school is making you do, think of it as a choice. You are choosing to revise because you want to learn, develop your understanding of a topic, improve your grades, etc.
3. Set clear work boundaries.
Make sure you set aside time for work, and time for rest. During work time, you are focusing as much of your attention on revision as you can. During rest time, you aren't thinking about work at all. Try to avoid "grey time" where you are sort of working and sort of not. This will leave you feeling drained and dissatisfied, and eats away at time where you could be properly relaxing or having fun. Something that helps me is having different places for work and relaxation. E.g. you could work in a library, or in the kitchen, and relax in your bedroom.
4. Overcome the hurdle of starting work.
Starting is possibly the hardest part, especially when you have no motivation. You really just gotta think "screw it" and get on with it. The more you're able to do that, the easier it will get. It helps to find a good work space and eliminate distractions (e.g. by turning off your phone). If you find it easier to work with another person to hold you accountable, see if you can meet up with a friend, or play one of those "study with me" youtube videos in the background. Something that might help you to overcome the hurdle of starting work is to tell yourself "I will only work for 2 minutes". This makes it less intimidating to start. Once you've done 2 minutes of work, you might have got into the swing of it and find it easy to continue. If not, allow yourself a break for 10 minutes, go for a walk, have a snack, then try again for another 2 minutes.
This turned into an essay, oh dear xD I hope you find something in this that's useful. Take good care of yourself - eat well, sleep well, do some exercise, and make sure you take some time to enjoy yourself and have fun this half term. Wishing you all the best!
