Can I sue for a full refund even if parts of a contract have been fulfilled?

You are only entitled to the damages you sustained by reason of the photographer's breach, by your estimate 1/4 of the total price.  You also may be barred from suing by the statute of limitations.  I don't know what the limitations period on breach of contract is in Maryland, but in many states it is less than 5 years.  I don't know when the photographer's performance was due, i.e. when the breach occurred, but if that breach occurred longer ago than the limitations period, and you have no basis to extend the limitations period (in rare cases the limitations period may be tolled, or the defendant may be estopped from relying on it, for reasons too complicated to get into here) your suit will be dismissed.  If you sue in Maryland, you may not have to appear if you settle the case early.  However, if the defendant wishes to, he can almost certainly force you to appear in Maryland, for deposition and/or to testify at trial.  However, unless your conrract prohibits it, you may be able to sue in California, depending on whether the photographer has sufficient contacts with California to provide a California court with jurisdiction over him.  If the photographer has been dealing with you in California about this matter, it is entirely possible that his contacts with California will be deemed sufficient.