Legal Question in Civil Litigation in California

That doesn't sound like a good reason. The person responding has to say why it's unavailable such as: "Responding party has diligently searched for such document, but is unable to locate it. Responding party is informed and believes, and thereon alleges, that such document at one time existed, but has been lost, destroyed, or misplaced. Discovery and investigation is ongoing." The responding party also should say, if he/she has never had the document, where the original might be. You might review the Code of Civil Procedure to determine the required elements of a response. Otherwise, a motion to compel might be appropriate if the document is one critical to your case. Of course, it's important to utilize your resources wisely. A court might grant a monetary or issue sanction if the court is not convinced of the responding party's wisdom in its response. Likewise, it could issue a sanction against the moving party if its motion is without merit.

A motion to compel further responses to inspection demands is appropriate when the party responding has provided a deficient response. A statement of inability to comply with a demand for inspection must affirm that a diligent search and reasonable inquiry has been made in an effort to comply with the demand. The statement of inability to comply must specify whether the inability to comply is because the category or itme has never existed, has been destroyed, has been lost, misplaced, or sotlen or has never been, or is no longer in the possesssion custody and control of the responding party. The response must also identify the name and address of anyone believed to have custody control, or possession of the demanded category or item. (Code of Civ. Proc., sect. 2031.230.)

If the response fails to comply with these requirements, you may file a motion to compel further responses.