As far as I can tell they are both working perfectly. I am not getting any beep codes telling me anything is wrong.

It connected and worked fine yesterday, before I took my PC to my mates place. I did not take the monitor, I used his TV.

The monitor is recognizing the PC. When I remove the cable from the PC it displays on screen "check cables" but when I put them back in still nothing happens.

I do 'Not' have another monitor to check the monitor, but the monitor seems to be in full working condition anyway.

The ports on the PC are fine as well so I'm really confused.

The PC is also newly built with all new parts. I have also checked the power cables to see if anything became loose but nothing.

Can anyone help me?

What type of connector are you using (i.e. VGA, DVI, HDMI)? Does the monitor display anything when it first turns on like the BIOS loading screen? You can try reseating your CMOS battery to clear out BIOS settings to see if that does anything.

Try going into safe mode and adjust your graphics back to what your monitor can use. Your mates TV may have caused changes to your settings that your monitor can't handle. 60Hz instead of 120 Hz widescreen versus standard etc..