CPU is on but Monitor is on sleep mode

Hello, I have a Samsung LED monitor the problem is that the CPU is on but the monitor is not lighting up but the red light near the buttons is blinking i read the manual for the monitor and it said that if its blinking its on power saving mode we bought this monitor just yesterday and yesterday it worked properly now the next day i turned on my PC the monitor is on power saving mode i unplugged the monitor and replugged it but its still in powering saving mode.....My suspicion is that my CPU is now very dusty and some components are now filled with dust and may have blocked the monitor to recieve signal to the monitor....i will get it cleaned tommorow if its cleaned and fuctional properly ill report back and if it dosent its something else also i heard no beeps so its not hard drive also the CPU is all ob like all its components are working fine although its actually quiet than usual like 10x quitely also i took my phone and flash light the inside of the my PC since near the fan is glass soo when i lighted it it was dusty as my attic upstairs soo please tell me whats wrong...