A person can lose the right to own or possess a firearm in several ways, and there is no easy way to get your firearms rights restored.
First, a person convicted of any felony criminal offense loses the right to own or possess a gun. Second, anyone convicted of a misdemeanor crime involving domestic violence loses their gun rights. Third, anyone involuntarily committed for mental health treatment or found not guilty of a crime by reason of insanity will lose their gun rights. Finally, anyone who is subject to a restraining order (can be called a Protective Order, an Anti-harassment Order, or a Domestic Violence Protective Order) will be barred from possessing guns.
When a person loses their firearm rights, it becomes a crime for them to own or possess guns, ammunition, or even parts to firearms. A person could be charged with the crime of unlawful possession of a firearm even if the weapon does not belong to him/her (for example: a situation where a spouse, roommate, or friend stores their weapon in the place where the person lives). A person could also be charged with a crime even if they did not know a gun was nearby (for example, a person borrows a car from a friend that contains a gun in the glovebox).
Because of the constant risk of being charged with unlawful possession, some people choose to have their gun rights restored even if they never personally intend to own a weapon in the future.