My mother recently died and my siblings claim there is no will although my mother talked about her will before she passed.

My mother recently died and my siblings claim there is no will although my mom spoke of her will before she passed. I am concerned because her will should also provide details on where our brother who is developmentally delayed is to live. I did call the probate office in her county to determine if a Williams filed and they found her name and town with a filling date but nothing else. The clerk discouraged me from coming to the office to look for the file. What should I do?