Display is black but sound works

From all videos, via youtube, via facebook, all other video sites, and also in windows media player, the display is black but the sound is displayed. Advertisement images and subtitles are also displayed. This problem is suddenly the case after the computer has made a clicking sound and the computer was locked while playing a video on youtube. After restarting and having done the necessary security scans, no video image is displayed, except with the VLC media player. I have checked the driver of the video card and I get the message that everything works correctly there.

My computer is a laptop with windows 7 and firefox. Flashplayer version is 27.0.0.187.

I would like to hear from you how I can further test flash player for errors.

Regards,
Bennie Hansson