Ive a bump on lingual frenulum. no idea on what caused it. how can i cure it?

Salivary gland issue: There are salivary glands in this area of the mouth. They can become blocked/obstructed, inflamed, infected. This is a difficult place to see well yourself, even using a mirror. It is not likely to be anything serious, such as cancer, especially at your age and if you don't smoke, but you should see an ENT (ear/nose/throat) specialist. Good wishes:)

Does it hurt?: If it hurts, could it be a cold sore? If it doesn't hurt, has it grown? When did you first notice it. Most of the time you may have had it for a long time and it is completely benign. If it hurts and/or if it is growing, time to see your dentist.

Suspicious Bump: I would advise you to have the bump on lingual frenum examined by any dentist or dental specialist (e.g. oral surgeon, OFP), to help you with a diagnosis and treatment, if needed.