Monitor Black, Green Power Light Flashes Monitor is 4 yrs. old

I began having problems with my monitor about 4 months ago. I turned the monitor off and it stayed bright white and did not go black. The entire screen was a big white light!! I had to leave the monitor turned on because it lit up the entire room. Several weeks later, I tried to turn it off again, and it turned off correctly. I noticed in the top left corner, the screen was flickering. The screen display was still pretty good. It continued, so I decided to turn it off. It went off fine, but will not come back on. The green power light seems to flash 4 times, then short break, 4 times, break, etc. There is no type sound coming from the LCD. Any idea what the problem may be.