Monitor not detecting tower after working fine 24 hours ago

[aperez440]

I built my first PC yesterday and everything was working fine. Today I unplugged all the wires that were entering the tower and then plugged them back in. After doing this the monitor now gives off a HDMI-MHL 1 not detected. Im not sure what to do since everything was working fine before. Any ideas?

 

[Chaska]

If you have a graphics card, which your tags seem to indicate, you could try reinstalling it. If that doesn't work, plug the monitor into the motherboard if it has on-board video output. Does the computer seem to power on (fans start spinning?).