I've tried connecting the pc with VGA cable . The same thing happened . I want to mention that when I plugged on the monitor my ps4 , ps3 and a DVD all where displayed as they should be .
Just now I tried connecting the PC to my main TV and everything looks ok . The colors are as they should be . I connected it using the same cables , first with HDMI and then with VGA. Everything looks fine . So I believe it is a monitor's fault. I also doubled checked if the colors were fixed after trying it to my main TV as I said .Nothing changed the colors looked the same on the monitor. I suppose it is solved....