Itu2019s not clear what you mean by u201cfile a complaint.u201d As Tom Willcox pointed out, you can file a complaint with the State Bar of California: How to File a Complaint Against an AttorneyIf you mean a civil lawsuit for legal malpractice, you can do that by yourself also, but you would be better off talking to another attorney first. Most attorneys will offer a free consultation about a case.Run a Google search foru201dCalifornia legal malpractice attorneysu201d if that is what you meant, and you will get multiple hits.