No one said it did.the only way to change or repeal the 2nd is with an amendment that directly does that and the 14th doesnt mention the 2nd,,
In Barron v. Baltimore (1833) the Supreme Court held that the Bill of Rights applied only to the Federal government, not the states and local jurisdictions – including the Second Amendment.
Residents of the states could not bring suit in Federal court to challenge the constitutionality of a state’s firearm regulatory measure on Second Amendment grounds.
With the ratification of the Fourteenth Amendment, pursuant to substantive due process, the Supreme Court began to incorporate (apply) portions of the Bill of Rights to the states and local jurisdictions.
When the Second Amendment was incorporated in 2010, residents of the states could file suit in Federal court to challenge the constitutionality of state firearm regulatory measures on Second Amendment grounds.