Unfortunately, under Ca law you have to find the will or it is presumed that it was destroyed if it cannot be found. Look through his papers to see if you can find the will, or a bill from an attorney that you can contact to ask if he prepared the will. Look to see if he had a safe deposit box or a safe that it could contain the will. Use as much common sense as you can to think of where he may have kept the will. Check with his accountant, financial adviser, or banker also.
Any individual seeking legal advice for their own situation should retain their own legal counsel as this response provides information that is general in nature and not specific to any person's unique situation. Circular 230 Disclaimer - Advice given in this response cannot be used to eliminate penalties with the IRS or any other governmental agency.
If you cannot find a will, you can initiate probate proceedings using the rules of "intestate succession". Under those rules, your uncle's closest living relatives (his sister and the children of any deceased siblings) would be entitled to the entire estate if your uncle was not married and his parents were not alive.
I've handled probate matters as far north as Mendocino County and as far south as San Diego County. If you need assistance, please contact me.
The information you obtain at this site is not, nor is it intended to be, legal advice. You should consult an attorney for individual advice regarding your own situation.