I have an HP computer with a 19 inch monitor. Yesterday I was on it and all worked fine but this morning I turned it on the tower came on but when I turned the monitor on, the light was green and in less than 30 seconds I heard a click and the light turns yellow. The monitor never lit up, it was like it went to sleep before it came on. Checked connections and tried turning it on and off several times. Monitor gone bad or what? Thanks.