Don't confuse a true hit-and-run accident with another situation. From time to time, a driver might, for example, be attempting to negotiate his car out of a very tight parking space. In the course of backing up, he accidentally taps his rear bumper against the car behind him. Zero damage is done to either car, and the driver, breathing a sigh of relief, finally extracts his car from the parking spot and zooms off. While those types of incidents are best avoided, they aren't the type of accidents being discussed here.
A hit-and-run in this scenario refers to a situation where, for instance, you are sideswiped on the freeway and the other car speeds off without a backward glance. Or you return from running an errand only to find a tremendous dent in your rear bumper, or a large scratch running along the side of the car. In other words, any situation in which a car is damaged by the driver of another car (or in rarer circumstances in which a car comes into contact with an inert object such as a wall) and that driver does not either leave contact information or remain at the scene. Know that when this occurs, the driver who did the damage is in violation of the law.
If you have been the victim of a hit-and-run accident, it's smart to write down as many details as you can at the moment. Note the time of day you discovered the damage, the location and if at all possible, get the contact information for any witnesses. If you happen to know any details about the car that hit you, make sure you write those down as well. It's also worth your time to file a police report.
You may also wish to consult a personal injury attorney. Insurance companies are not always keen on paying. They are also hard pressed to value compensation for pain and suffering caused by a hit-and-run accident. If you cannot come to terms with your insurance company or would like more information about whether you are entitled to additional compensation, you may wish to discuss your case with a personal injury attorney.