The Legend of Zelda: Majora's Mask/Clock Town

Back to the First Day
As soon as you play the Song of Time, you'll be pulled backwards through time and find yourself back in Clock Town, only things have changed: it's the First Day again! When Tatl sees this, she gives you an apology for what she did to you before, and starts helping you on your quest. However, even after this, you're stil a Deku Scrub!

The Song of Healing
The curse on you needs to be broken, but there seems like there's no way to do it! However, you're very close to the answer. Go into the door right behind you, and you'll be in the Clock Tower Basement again. The Happy Mask Salesman is still here, and sees that you've returned. Excited, he gives you a nice greeting, but then goes and pulls out an organ. With it he teaches you a new song, the Song of Healing.

The Song of Healing  is:

The moment you play this song, the curse on you will break, and all that will be left of it is the Deku Mask. You can change into a Deku Scrub anytime you want with this mask and assume its abilities.

Unfortunately, when the mask salesman learns that you didn't get the mask back, he'll become furious. After shaking you down and yelling at, he says that losing that mask was a terrible mistake because it holds horrible powers, and it could be a disaster if they were released. After a long conversation with him, leave the basement and return to Clock Town.

The Great Fairy Mask
When you re-enter Clock Town, go down to Laundry Pool and catch the Stray Fairy again. The Great Fairy told you to come back now that you've returned to normal, so head back to the Fairy Fountain in North Clock Town, and when the Great Fairy re-appears, she'll give you the Great Fairy Mask, which makes Stray Faries in temples come to you.