There is also the question of causation. In order to hold someone liable for an injury you suffer, you must first be able to establish that but for his particular action, you would not have suffered the injury.
So you now claim that if you had been lawfully able to carry a gun, you would have been able to successfully, under the exact circumstances of your particular incident, defend yourself and avoid injury. That can be a pretty tall order. For example, could you prove to the satisfaction of a jury that had you been able to lawfully carry a gun, you would have been carrying it at the particular time? Could you show to the satisfaction of a jury that you had the level of training and skill necessary to effectively use your gun under the exact circumstances of your incident? Could you show to the satisfaction of a jury that you would have used your gun effectively enough to prevail and escape injury? Remember, sometimes good guys fighting back still get hurt, and sometimes good guys lose.
Basically, what you could have been able to do under particular circumstances is too vague and speculative.
And of course, that's only one possible legal hurdle. The short answer is that a claim such as the OP proposed really doesn't have any legs under current law.
