i don't know where my spouse is

california

i don't know where my spouse is, can i still file for divorce?

I would suggest getting an attorney because this complicates things -- not terribly but it does add some compication. You can file for the divorce and "serve by publication" meaning publishing notice of the filing in a newspaper as outlined by statute....this vaires by state as to location of the paper, duration of notice, etc (one reason to have the attorney) and there are usually several criteria you have to meet before you can serve by publication (the other reason for the attorney).....such as making a "good faith effort " to locate your spouse (ie contacting any friends/relatives you know of, etc)......
Your best bet is to see a family law attorney and lay this out for them to give you an opinion on - -most offer free initial consultations so you can get an idea what lies ahead without it costing you $$$ and you can then decide if you are comfortable going on your own or if you want to hire the attorney.....