I think you're quoting a line from a Mariah Carey song. If so, "time melts into nothing" should be read in context of the lyrics:
You look in my eyes
And I get emotional inside
I know it's crazy
But you still can touch my heart
And after all this time
You'd think that I
I wouldn't feel the same
But time melts into nothing
And nothing's changed
In other words, what "time melts into nothing" means here is that "so much time has passed that I thought I would no longer feel anything for you, but when you look into my eyes, it is as if time had not passed at all (the long period of time 'melts into nothing,') and my feelings for you are still the same."
So here, "time melts into nothing" = "it is as if time had not passed at all."