My brother sold our shared flat in Mumbai without informing me?

I just found out that my brother sold our shared flat in Mumbai without my consent. We inherited this property from our parents, and I've been living in Delhi. He didn't inform me or take my signature. The sale was completed last month, and I am extremely frustrated and feel betrayed. What can I do legally to challenge this sale and reclaim my share? I need advice on how to proceed. Should I file a case in the Mumbai court?