I haven't seen either of those, but maybe She Was Pretty - ML was a chubby child, but grows up handsome. FL was beautiful when she was young, but loses her looks as an adult.
I think the ML in Meloholic used to look nerdy but only in the 1st ep? It's been a long time since I watched that. But the FL also changes looks since she had a different persona
Dream High - ML starts out as a country bumpkin with long, wild hair. He gets TWO make overs.
Pinocchio - ML starts out as a country bumpkin with long, wild hair and a somewhat awkward / ridiculous personality.
Moon Lovers: Scarlet Heart Ryeo - The FL uses her modern day makeup skills to help the ML hide a large scar on his face that previously caused him to be treated as a monster and an outcast.