First of all, you must appreciate yourself for the fact that you have finally come to self realization without being too late. 4 years wasted - I would like to say that no year is a waste, you always get to learn something. I hope these 4 years were at least crucial for bringing you to a point of self realization. Hence, 4 years have not gone into a waste.

Now coming to guidance, I would suggest you to join an Offline Banking Preparation Classes (Coaching). Not online, but offline. If offline is not possible, you may go for online. A coaching class is a must because without proper notes (lecture notes as discussed by the teachers in the institute), it will be very difficult to get an entrance exam (by solely studying from textbooks, which are difficult to revise). Apart from notes, you will get to know what exactly to study and what to leave from the teacher. Also, regular mock tests will force you to study regularly so as to perform better. These things will help you crack a Banking Exam.

Now coming to "studying regularly"- believe me noone likes to study. Without motivation, guidance and some sort of pressure, you wont be able to study. A coaching class will provide you with the needed motivation so that you will be able to study in a disciplined manner. Also, it will take time to get acquainted. You will have to do some sacrifices like leaving social media, quitting smartphones, but in the end these sacrifices will be worth it. A good study timetable starts early morning (from 6/7 AM) and includes proper 8 hours of sleep (preferably 10 PM to 6 AM) daily.

Also, I would like you to stop comparing yourself with your friends. Remember there are examples of many people who got settled late, but in the end became very very successful. You should learn to compare with yourself. Your tomorrow should be better than today - in terms of learning and knowledge. By improving bit by bit everyday, a day will come when you would have acquired so much of knowledge that you will be able to crack lots of Banking Exams. This will take time and patience.

Now coming to English, use the a pp knudge (from playstore) which will help you in improving your vocabulary. Also read Normann Lewis - Word Power Made Easy. Watch good english movies and newpaper editorial discussions on YouTube every morning. Also, your coaching class will help you in improving your English.

Finally, I would like you to talk with your parents on a daily basis and share with them your emotional disturbances. You will feel much better and relieved - because when you share happiness, it multiplies and when you share sorrow, it divides.