Monitor turned bluish purple-help

Do you use VGA onboard or Addon ..?

I suggest you return it. Borrow another monitor first and test it to make sure it's not the graphics card that's faulty.

If this is a new monitor then follow Herr_Koos' suggestion and test if it isn't your graphics card that is faulty. If you graphics card is fine return it.

If it's an older monitor then it's time to get a new one. I had a CRT monitor that couldn't reproduce the red color anymore, I could see only blue, green and yellow. I tried to fixed it but it broke after just a couple of days.

Check the cable.
CRT or TFT?

^check all cabling first, yes.
then return as per Herr_Koos..

No bents pins on the headers?