LG monitor power saving mode

Hello,

I have a gateway desktop that I got from my cousin and it's amazing for gaming. So, I'm pretty sure, it's custom made.

I unplugged some things to clean my room and when I tried to plug them in again, the computer would turn on along with an error message on the monitor.

It says that the cable I just plugged in is plugged in "power saving mode". This has happened once before which I came to this exact website and followed some instructions that I listened to and it worked.

However, the solution is not working this time. I've turned my PC off so many different ways that I'm scared I might have damaged the power supply.

Please help!