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.
Follow the below tips to prepare for SBI PO :-
For more detailed preparation tips for SBI PO by our experts, you should refer to the link given below :-
https://competition.careers360.com/articles/sbi-po-preparation-tips
I hope this information helps you.
Good Luck!!
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