How can I regain my focus ?

Well 11 days is not enough to regain. Try to be more committed to on thing at time and slove that thing then move to onother.

 

Don't wait for the perfect moment bro. Just start studying. As if you will relapse in this stage so you will have lots of regrets. For example, Suppose you give your full efforts and you didn't do other works and did NoFap till 12 days and then relapse, so your efforts are gone to zero and at that 12 days, you have not done your priority work too. So bro study every day as if you will relapse after 12 days then you have studied for 12days...right? rather than just doing NoFap. Also, one can have long streak only when they shift their focus from this into other. In our case, it is studying. So Study Hard!
Btw I am too struggling with studies..lol. But will surely Study Hard! Let's Go!

 

Hello. I too have burned out my attention span and have been slowly recovering. Here's a couple of tips.

You won't regain your focus right away. If you spend loads of time distracted, your brain will get rewired to favor distraction and jumping thought-to-thought.
Accept that it won't be easy and that it will require effort and time to restore your capacity for focus.

Start doing a "slow" activity in (initially) short bursts. Rewiring your distracted brain for focus is the same as strengtheing up a weak body: you need exercise, as uncomfortable or boring as it sounds.
The top activity in my opinion is meditating, as it is, basically, immersing yourself in nothingness, yet if it doesn't work for you, other less stimulating activities might also be beneficial. Off the top of my head I'd recommend drawing (any kind of art, really), reading or going for walks.

Make your distracting activities more difficult to engage in. Often we resort to distraction because of laziness, and you'd be surprised at how much the stimulus to engage in these activities was reduced when I made it more cumbersome to engage them.
This might mean turning off your phone when you study, unplugging the TV and/or gaming console and installing website blockers on your internet browsers (for Chrome I recommend the extensions Forest and StayFocusd).

Engage in more meaningful activities to de-stress or to eliminate boredom. Stress and boredom are responsible for 99% of my distraction cravings. I found a tactical advantage in this, since I was able to "substitute" my distracting activities with better ones, since I didn't do these things for their sake, but to stave off boredom and stress.
To give you a practical example, when I'm stressed I tend to listen to music or watch dumb YouTube videos, alone. I got concious of this, and now, when I get a craving for YouTube, I know that, in reality, I'm just stressed, so I act accordingly and do something better, like playing with my cat or calling my friends.

This is what is helping me and I hope it helps you too. However, don't take it as a set of unbreakable rules, as everyone is different, and what worked for me may not be helpful to you.
May your focus reflourish and bloom. Peace.