How do I cure lichen planus?

Flagyl. If this is lichen planus you need to be tested for associated problem as hepatitis c. I have good experience with oral flagul which needs to be used foe several months to flatten the lesions and lighten the residual color. The mechanism of action is unknown.
Skin disease. My best advice is to see a dermatologist who will biopsy the lesion to confirm the diagnosis and then prescribe appropriate therapy.