Hi sunil,
Starting the preparation from scratch in the age of 20 for banking is not late at all. It is just a fear or a doubt in yourmind that is not making you to move forward. You can start your preparation from scratch and crack the banking exam easily.
Even if you are weak in general aptitude and English you can pass the exam by preparing sincerely with sufficient efforts. Though it seems that syllabus of english and general aptitude is vast but it is not that much difficult that you can not cover the topics in one year of regular studies.
You just need to set your goal. Fix you time table or study plan. Decide from which chapter you want to start your preparation and start preparing. Unless and until you will not try you will not know your abilities. So just start preparatin without thinking any negative point about yourself.
If you find difficulties in understanding some topics you can take help from the expert or teachers in that subject.
Hope it helps.
All the best.
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