Despite the fact that both cities I listed are rampant crime holes, showing what happens when citizens can't legally protect themselves, let's look at the premise of your agrument.This sounds wonderful in theory, I agree. As stated before, if I was 100% guaranteed that the anyone else could protect me and my family, without my guns, as well as I can protect myself with them, I'd give up my firearms in a heartbeat (even my recreational guns that aren't used for self-defense.) The problem is you cannot successfully ban guns, not in a single city OR an entire country. You can stop selling them, but people will still have them. You can demand registration, but people won't comply. Do you realize that it's even entirely possible to make a gun from scratch?
Assuming all guns magically disappeared, we would simply have more crime with other weapons. The difference would be that without the gun there is a disparity of a force. The gun allows the old, the weak, and the few to stand up to the young, the strong, and the many. In a world without guns, those with regard for the law would have no protection from those who do not.