USA

Hi Radhika,
Yes, you can pursue studies in any area of your interest. Irrespective of the field you choose you must take the SAT and TOEFL for gaining admissions. You must also present a strong statement of purpose stating your reasons of the shift from commerce to psychology. Most importantly you must have good grades to land up in a top university. Check various university websites for a better understanding of admission requirements and process.
Some of the best universities for UG degree in Psychology are University of Minnesota-Twin Cities, University of Illinois-Urbana-Champaign, University of California-Los Angeles and Princeton University to just name a few.
I hope it helps. Do write back for any assistance.

Hello Tejas, the best way is by narrowing down your choice - check the amount of expenditure in each country and various universities and see which one fits your own budget. Check the admission requirements if it matches with your profile. These three countries are some of the best places for MBA so you must make a checklist and match those with your budget and requirements. Also remember that the duration of MBA programmes in USA is 2 years while in Australia and Canada you will find programmes lasting from 1 to 1.5 years, this will automatically lessen the budget. Keep referring to MBA world rankings such as Financial Times Ranking and so on. I hope you can make a calculated decision now. Good luck.