Memory

I hate not being able to remember things.
No, i don't have memory loss, its just that i can't recall things.
For eg. I tortured myself for 6 months trying to remember a song of which i remembered just one line- "i just want u to know who i am." i didn't remember anything before or after the line. Not even the tune. I finally found the song on my bros laptop and my soul rested. I'd actually heard that song around 2 yrs ago for the last time....
Then, i was haunted by the line "you love me, but you don't know who i am." i found out the name of the song on the radio.
Nowadays, i can't remember what i'd been thinking about a minute ago. I get lost thinking about something, and when i wake up, i forget about it.
And yes, another line whose song i can't remember- "you can touch, you can play, you can say i'm always yours."
Please help me. Which song is it from?