So it’s been a while since I last used this website… the reason for that is that I have an extreme lack of concentration and focus I can put into one thing. Before I had this account I owned 2 other accounts which I used a few years back.
So my question is:
What to do when I lose focus and concentration on coding and I stop using it for another few years?
Everyone is different, but try to take regular breaks. Don’t try force yourself to smash it out, once your concentration starts to go take a break.
If you get stuck walk away for a bit too, rather than running it over and over again in your head getting no where.
Try to have a purpose or find a way to make it fun. Like you I started to learn, in my case python, twice before but didn’t stick at it then I had an incentive and challenge that got me through the initial learning stages.
Think about how you learn and try to learn that way.
Well, sometimes, learning too much can be overload or frustrating, and you may want to take a break (which makes sense… I took a break from coding). 
Sometimes, it’s best to start over on some lessons and/or review things and get a new perspective on the course, or maybe start learning something new.
You can find a time where there are no distractions and you’re able to find a focus. Coding in a place like the library for instance… It’s quiet.
You don’t have to shove in a ton of lessons a day, just taking it slow (like a doing a couple lessons) is a great start. For beginners, taking some notes while doing a lesson can help you stay on track, and setting goals also encourages you to stay persistent. 
I hope this helps
Best of luck with coding! 
Are you having, or did you have the same trouble in school? Did your teachers give up on you? Which teacher stands out as having the most empathy, being the most helpful and motivating? What did they do to help you gain focus or pay attention?
School is something forced, I was always one of the first to be done with my work, it wasn’t something that requires my concentration, so no I didn’t have any problems. At least if it wasn’t about grammar.