If someone died in the US and left a will, you have to go to the state they died in, know which county (or parrish in Louisianna), and go to the probate court for that county. They should have books that you can look that up in. Unfortunately, one of the problems with the US is that each state has its own way of doing things, and that some states have practically all data on line, some have none and some (like Massachusetts) have portions. But you have to know where most specifically they died, and then contact that probate court (phone or writing). Wills have to be filed with court. Getting someone to look for it might be an issue.
Teri