Why doesn't my screen display a video, What should i do if my screen is dark – Sony VAIO VGN-FW User Manual

VGNFW590GKB, VGN-FW550F, VGNFW599GBB, VGNFW590FWB, VGNFW590G, VGN-FW510F, VGN-FW520F, VGNFW590H, VGNFW590, VGNFW590FYB, VGNFW590FFB, VGNFW590GHB, VGNFW590FVH, VGNFW590FET, VGNFW590F3B, VGN-FW560F, VGNFW590GMB, VGNFW590GUB, VGNFW590FDB, VGNFW590FSB, VGNFW590FFD, VGNFW590FFT, VGNFW590GJB, VGNFW590FXT, VGNFW590GAB, VGN-FW548F, VGNFW590GNB, VGNFW590F2B, VGNFW599GCB, VGNFW590FZB, VGNFW590FVB, VGNFW590FRB, VGNFW590GGB, VGNFW590FDH, VGNFW590FPB, VGN-FW518F, VGNFW590GLB, VGNFW590F, VGNFW590GTB, VGN-FW530F, VGNFW590FEB, VGNFW590GIB, VGNFW590F1B