No signal to monitor - ram clean/fix not working either

Hello, the problem first occurred when I turned off my computer and started it again an hour or so later, it started but showed a no signal to the monitor. I restarted the computer and it happened again so I searched over the Internet and it said that I should clean my ram so I did but it yet didn't work, I cleaned it again and again but it still didn't work so I thought it might have been another problem. I've tested taking out the power cord to the computer and holding the on button for about 2 minutes and it still didn't work. I have no idea what the problem is. Please help.
Thank you.

-Andy