Uninsured/underinsured motorist coverage is a special type of car insurance that protects you if the person who caused the accident does not have any insurance, or not enough insurance to cover the damages. It is part of the required minimum insurance in some states, and available as a rider on auto insurance policies in other states. This can be an invaluable type of coverage to have, but it is not of much use when you are found to be at fault.
If you are found to be at fault, the coverage that will repair damages to your vehicle is collision insurance. This is available as a rider the same as uninsured motorist coverage, but applies to physical damage to your vehicle, not to the cars of the other people involved in the accident. Because collision coverage increases the amount of your auto insurance, it may not be beneficial to people who own older cars where the cost of damages may exceed the book value of the car itself.
Where uninsured motorist insurance would be beneficial to you is a situation where someone else caused the accident, and that person did not have insurance coverage on their vehicle. In that case, uninsured motorist coverage would pay for personal injury and property damage costs up to the limit named in the coverage.