hi,

see suicide is not a solution to any problem, so never think of it, have you encountered with any physically disabled person or any blind person, who are continuously trying to do some works or want to become self dependent by doing something, see age 20 is not a big age that you should start blaming your self for doing nothing, this is  just starting if your life.

now coming to ca exam, CA has three steps and also it required to complete CA intermediate before appearing for ca final exam, now sbi po and ca exams both are different and CA syllabus is comparatively hard then any graduate level competitive exam , but you should give mock test and prepare strictly for sbi po exam since numerous students every year appear in the exam. so now decide which exam you should opt for and start preparing.