1). Bird of white wings was landing to the poplar - A bird of white wings was landing ON A poplar (and, rather "landed" then "was landing", but the size of the line will be too small)

2). I fell in love with -A- young and handsome violinist

3). Sounds of music lost somewhere among the trees - that's right, WERE lost (The Passive voice is needed)

Maybe: Sounds of music were lost there among the trees

4). Not for me played but for some another girl - either "for another girl", or "for some other girl"
Maybe: Were not for me, they were for another girl.
Or
Not for me played, they played for another girl
Or maybe you'll make up something more lyrical :)