Did I sign away my inheritance?

When I was 14 years old I signed a legal form I believe was to give my stepgrandmother permission to take control of my grandfathers money. He had an irrevocable will and while he was in a rest home after having a stroke she had everyone in the will sign a similar form. She was then able to sell his properties and buy homes etc. My parents told me to sign it or they were afraid my Dad would lose his job. My Dad worked for the family business. My grandpa passed away shortly after and we are estranged from the family. Where can I find a copy of what I signed? My parents never kept a copy and I don't even know what it said. Is there any way I can find out what was left to me in his will? I would at least like to know what he left me. My stepgrandmother is still living so I assume she changed everything. How can I find out what was in the original will? This was in Los Angeles County. Thank you.