My laptop screen has bands of dark blue and yellow or else of the right flag. How do I fix it?

Near are 4 possible variants:
1) Broken matrix of the LCD blind
2) Broken backlighting of the matrix (mayhap one of the lamps has broken, I had related trouble)
3) Also perhaps several cords, connecting peak with motherboard, can metal broken
4) Faulty videocard
So, take it to the service center and they can exactly identify the cause of your troubles.