Question Monitor says "No Signal" after changing the refresh rate to 144Hz ?

[CreampuffBoy]

I was messing around with the Refresh Rate on my MSI G321CU 4K Gaming Monitor in the Windows display settings and I changed it to 144Hz to try and get rid of the grainy/fuzzy look the screen had, but all of a sudden my monitor no longer displays anything.

Windows display settings does not let me change anything on it and registers it as connected to my RTX 4090 GPU, AND the monitor constantly black screens and says "No Signal" even though it is still connected to the same port it has always been connected to.

Questions:

1. How do I bring the picture back to the screen and get Windows display settings to register that it sees it as no longer inactive ?

2. How do I fix the grainy issue with the screen/resolution ?

 

[CreampuffBoy]

Update: I have fixed the issue but now I still have a problem. Things on the screen still look grainy on the edges but is that just because I have this monitor (which is set at 3840 x 2160 native resolution) flipped vertically or is it something to do with the monitor's settings?