Forged will.

Hello SIr, My father had recently expired in the last week of april 2016 and later on my fathers brothers took away all the belongings and documents related to assets in the absence of our family members (i.e mom,elder brother and myself) and now upon that assets information whatever they are having they had created will dated on 2013 January stating that entire my father properties is equally on their deceased mother, deceased brothers daughters /sons.without mentioning our names. As one of my fathers elders brothers is retired S.I and younger brother is advocate by using their criminal thoughts they are giving hard time to us.Can i challenge that unregistered will against my fathers brothers and whoever involved in this.Can you please suggest me the best way to succeed in this. Ignore me if there is any grammatical mistake.