I have an hp pavilion computer and the monitor seems to be in sleep mode. The blue power light is blinking but the screen is blank and has been so for a couple of days. This has happened previously, but usually just when I first turned the computer on and after about 10-15 minutes.

Try to get hold of another monitor and hook it up to see if same thing happens - if another monitor does not do same thing, it is you monitor

If antoher monitor does do the same thing, it may be your computer may be overheating