I can relate to how you are feeling. I have struggled off and on the past few years with motivation, and also bad fatigue.
I think what is important first of all is to figure out the underlying problems or causes. For me I have been under a lot of pressure, both relating to school and family. When I get overwhelmed, I tend to start shutting down and wanting a break from everything.
It is also wintertime where I am currently at, which also affects a lot how well I feel (due to lack of sunlight). So I am now taking a vitamin D3 supplement, which I think helps some.
So questions that may help for this would be:
How long have you been experiencing this?
How is school going for you? Are you feeling any pressure or stress related to your schooling?
How is your current relationships with friends or family, or if you have a significant other?
Have there been any major or even small changes in your life recently that may be related to your lack of motivation (for example, a recent move, parents separation, diet change, etc.).
How many hours of sleep do you average each night?
How is your current diet? Do you eat healthy?
How often are you able to exercise?
Is it wintertime there or not as much sunlight?
I know how hard it can be to go through that, so I hope you are able to find motivation again. There can be many contributing factors to it. I find that when I take time to just relax and free my mind of all the cluttering thoughts that accumulate and pressure me, I feel a lot better. Today I took a sauna, just relaxed in it for a while alone, and it felt very good. Things that stimulate your sweat glands are excellent if you are under stress, so exercise or saunas or soaking in a hot bath are all very good for you. When you lack the motivation, any of these things will be hard to do, but it's worth it.
I am mostly speaking from my own experiences and what I have learned, though you might be different, so maybe these won't help. What is important is to analyze and determine the core cause of your lack of motivation. Once you understand the reason, it makes it easier to figure out how to get it back.