Start-up co-founder removed me from company without any notice!

I'm based in Bangalore and co-founded a tech start-up with a colleague. We've been working together for 2 years and recently secured funding. Suddenly, my co-founder changed all passwords and locked me out of the company's systems without any prior notice or discussion. I feel completely betrayed and don't know what my rights are or how to regain control. What legal actions can I take against him?