Hello Aspirant,
First of all, keep your hopes high. You've got the chance on this Earth as a human, that means you are able to do what you aspire, condition is that you should be determined and dedicated hard worker.
Feeling lost and hopeless sometimes is common, but you need to keep your will power strong enough, so that you can prevent this sadness from overpowering your soul.
Confide in a person (you said you've no friends, no problem, make one or talk to any of your peer sibling/cousin). Believe me, opening your feelings infront of someone helps a lot. The person will comfort you and suggest you from his own point of view.
If you feel that you can't crack the desired exam, keep it aside for a while and give yourself a new headstart with that exam as a challenge of life and you can do whatever you want to do.
Minimum age required to be eligible for SBI PO is 21 years and you are only 20, so you still have a chance to begin your preparation because there are many people who qualify SBI PO etc bank exams in their 1st attempt and that also in just 1 year preparation or even less, so even if you are starting from scratch you have plenty of time to prepare.
For English skills, use this lockdown period to gather and go through the online study material that will help you. Slowly and steadily, if you practice, you'll gain good English language skills.
Or you can go through following books and master the English language :-
Follow the below tips to prepare for bank exam :-
I hope this information helps you.
Good Luck!!
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