Problem with screen colored lines

Hi!

My phone has a strange, purple-and-white colored band on the lower part of the screen. I can still use the touch buttons, even if I can’t see them anymore under this band. The colored line is about 1,5cm (0,5 inches) wide, and there is another larger band 2cm higher. This second band is only slightly darker than the rest of the screen, and I can reed through it very well.

EDIT: I haven’t dropped my phone. The band started as a thin line, than in a week it grew to 3-5 lines and than after another 5-7 days it changed in a full-bar.