All I have is a vague memory of the music video.
1. I do not remember how the song sounds, who sings it, or what the lyrics are.
2. The song is sung by a woman. From what I remember, she had black wavy-ish hair and a black outfit. She was walking while she was singing. I'm not sure, but I think it was a playground, but I could be wrong. The music video was black and white.
3. The song was kind of slow and soft? I don't remember, but if I could compare it to another singer, I'd say it was similar to how Dido sings.
4. I heard this song on MTV Hits in the US between the years 2004 - 2008. I never heard that song anywhere else but there. It was a new song at the time I heard it.
I know this seems kind of vague, but sadly all I have in memory is part of the music video that I described here. Thanks for reading!