This problem has troubled me for a long time, I have learned guitar for 8 years and I cannot even reach 130 bpm 16notes. Recently, due to the suspension of the university, I get a lot of time to practice and I have to practice a song named “Waking the demon”, which focuses on tremolo picking and muting technique. So I decided to practice tremolo picking regularly, many sets of tremolo picking from low bpm to higher bpm ( starting from normal alternate picking). I practiced this routine on 17/2/2020, and today I find that I cannot even handle the alternate picking in low bpm. I am really frustrated, and I wonder how could I improve because I have tried different approaches to try to tackle this problem, and I already get injured so that I cannot generate any force from my wrist? How could I find a better and efficient way to practice? Thank you so much if you try to help me to escape from this hell 
I’m no doctor, but it sounds like you may have overdone it and burnt yourself out. Rest up for a week and see if you are in the same state. Don’t be tempted to play if you think you have injured yourself. If the problem hasn’t sorted itself out then definitely see a doctor or physiotherapist.
In the past I have done mammoth sessions with the metronome going from low speed to high and had very little to show for it other than sore arms and disappointment. I used to think that starting really slow would help, but all it did was fatigue my arms by the time I got to moderate speeds. Now, after I warm up I go straight to the highest known comfortable bpm and start from there. I use small focused time and try to avoid playing more than I need to on repetative exercises/practice licks.
I hope that this all works out matey - let us know how you get on…
Hey man!
Do not loose hope, such experiences are not uncommon.
I can think of two reasons which might cause you not being able to play today what you could kinda do yesterday.
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You tried a lot of different styles but you havent developed real conditioning, yet. So atm, because your brain hasnt really internalized a specific way to play as the “default-mode”, you start out at point zero, but will most likely lock in back into whatever you did the day before once you played around a bit.
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All the Ways (or the way) you tried to play require so much tension that playing doesnt feel “natural” until you have cramped up for a while. (I used to do this, no joke).
If you think this could apply to you, i suggest you focus on trying to find a way to play a more relaxed tremolo. Consider which muscles you really need to play a note, observe your shoulders, wrist, forarm for hidden tentions, which might seem natural to you, because you never played without them, but need to be overcome everytime you play a note. Read “The principles of the effortless classical guitar” if you want to (or search for other material on this). Some players here dont like the “reduce-tension” advice and consider it a byproduct which comes with bad form (pick position, etc). This is totally right, imo, but i also think that these better players wouldnt believe how much some people (like myself) unintentionally cramp up when we REALLY TRY to do something right. And if your tremolo isnt over 130BPM after 8 years of playing, something is fundamentally wrong, and considering your description of post-practice-fatique, i think its you cramping up muscles too much.
Of course, if you post a vid we could give better critique.
Why not find a good teacher?
I was in a similar situation as you last winter. I sprained my wrist snowboarding, and I couldn’t even hold the pick straight without shooting pain in my hand and fingers.
The best advice I can give you actually comes from the book “Steve Vai’s Guitar Workout”. If you have any pain whatsoever, STOP PLAYING. Take a break from guitar for a week or so, and then slowly go back into your routine. No matter how bad you want to practice — and I know it’s hard — no amount of time playing is worth any long-term injuries.
If the pain in your hands is still present but improving after the week of rest, take a few more days off playing as little as possible. If the pain is still as intense as it is now, I would highly recommend having a physician look at it just to be safe. Wish you the best!
Thanks for the advice! I would take a rest when I read books recommended by you guys 
In a normal situation, guitarists who do great in high bpm can also easily do great in lower bpm right? I think I am using different mechanics when I am dealing with low bpm and hight bpm. However, because of many reasons, I believe that we should use the same mechanics at all times and thus I have decided to practice from very low speed a long time ago until now. I am wondering if the concept is actually wrong.
I use the combination of wrist and arm to support my tremolo picking ( which is in higher bpm, I cannot reach above 100 bpm 16notes if I only use wrist), and only use wrist in lower bpm. 