Transition from 3 years Sales to Business analyst is it a wise decision? post transition can I expect a good salary ,currently earning 11LPA

Sales and BA require very different skillsets. It really depends on what you like.

Having said that if u start as BA its like starting all over again. Next company will evaluate only past 1yr experience and sales experience may not add much to BA job experience. If you have been a glorified telecaller at Byjus then definitely go for BA.