Complex sentence: Born left-handed, after losing 5 fingers in a lawnmower accident (and having four sewn back on again) on her left hand, she became used to playing a right-handed guitar upside-down, which contributes to her unconventional style of playing.
Split into simpler sentences: Born left-handed, she lost five fingers of her left hand in a lawnmower accident, and having four sewn back on again. She became used to playing a right-handed guitar upside-down, which contributes to her unconventional style of playing.