No signals to the monitor from CPU

Could be the monitor itself, the video card, or the cable that connects the monitor to the video card. We just have to figure out which one it is.

Start with the easy stuff. Turn off the computer and turn off the monitor. Disconnect one end of the cable and inspect the cable. Are the pins bent? Has the cat been chewing on the cable? If everything looks normal, reconnect that end of the cable and make sure it's securely connected. Now repeat the process for the other end of the cable. Turn on the monitor and the computer and see if that fixed it. If not, borrow another cable and try that one. If that didn't fix the problem, move on to the monitor.

Do you have another computer? If yes, connect the monitor to it and see if the problem follows the monitor. Use the cable from that other computer so we know it's not a cable problem. If the monitor works on the other PC, then we can rule that out as the cause of the problem.

Replace the video card and you should be good to go. The P6-20101X sometimes has an actual video card (PCI Express) and sometimes just the integrated graphics card right on the motherboard. If your Pavilion has a card, you can try removing it completely and connecting to the integrated graphics port. If you just have the integrated graphics port and no card, buy the (correct) card, install it, and you should be fine.