Want to know about my husband bank accounts and properties registered on his name

I was married in 2019 and this year in 2020 my husband died in a car accident. Although it’s just one and half year time span of my marriage i didn’t know how many properties or bank accounts is there on my husband name as he was a businessman by profession. Moreover I had 6 months child and now I’m so worried about his future. My in laws keep on saying we don’t know anything whenever I ask about it. My husband had two sisters and they also are married. How do I get details of bank accounts registered on my husband name and claim money in it. How do I get details of properties registered on my husband name and claim my share as well as for my child. Further more my husband registered our marriage before his death. I have PAN Card and Aadhar card details. Is there any way to get those details through these documents. Regards. Sheena