"Unreasonable" is the last thing you are being here. Indeed, paying any deposit up front is a roadmap to trouble, as you have already experienced insofar as you have waited months on what was supposed to be a two-week turn-around.
How did you pay him?
You are welcome to do as you please, but since you are having trouble contacting him, it is possible that he has not even started work on your knife. And since that is the case, I would suggest that you change your course of action from "patiently waiting for a quality knife" to "an immediate and full refund." If you stay your course, I suspect that there will be a lot more disappointment and frustration for you as well as excuses and inaction by him. However, if you demand a refund, then him not providing it to you immediately constitutes theft and he may be quicker to act when and if you choose to get the law involved.
Sorry to hear about this, but there are many quality makers who will make a knife for you without any deposit at all.