How to Fix a Crooked Nose?

Hi A,
The correction of a nose with a deformity like yours requires a complete evaluation of the structural components of the nose from the inside out.
The fractures you have sustained most likely has resulted in fractures of the bone at the bridge, and the cartilage in the septum. Often the cartilage of the septum is dislocated from its connections at the floor of the nose. This results in a complete shifting of the internal and external frame of the nose.
In correcting such a deformity. It would be best to begin by correcting the deformities, and fractures in the septum first. Next the connections of the framework of the sidewalls to the septum at the bridge, and then the bones.
With these methods, it is certainly possible to correct the appearance and give you your breathing back too.

Rhinoplasty is an effective and reliable way to correct the deviation or crookedness of your nose.  The extent of surgery will depend on the severity of the deviation.  
The nose is made of bone, and cartilage.  Sometimes it is one or the other that is causing the crookedness, but usually it is a combination of all of these structures.  In rhinoplasty surgery, the nasal bones are precisely manipulated to make them straight again.  With regard to the cartilage, there are several techniques used to straighten a deviated septum which acts as a pillar and a support structure in the middle of your nose.  If this structure is crooked, it can, and often does make the rest of the nose crooked.  Straightening a septum and keeping it straight in the long term is challenging because this cartilage has "memory" meaning that if you straighten it in surgery, it will have a tendency to go back to the way it was.  This is similar to the curled pages of a book, or a magazine.  Even when you uncurl them, or straighten them, they have a tendency to curl again.  
Nevertheless, there are techniques available to straighten the septum and nasal cartilages, and maintain this straightness in the long term.  I would recommend that you seek a plastic surgeon with a particular specialization in rhinoplasty and discuss your goals and available options. 

Fifteen years after the trauma your nasal appearance and function will not improve without surgical intervention. A good nasal surgeon will thoroughly examine your nose and then explain exactly what is necessary and establish reasonable expectations if you decide to have the surgery.
I always advise getting more than one consultation, carefully looking at each surgeon's results, so you can make a good educated decision in selecing the physician to do your work.