How is the display distorted? Colours/horizonal vertical shift/resolution/noise
Try these simple suggestions.
(1) Move the monitor away from any power source or speaker. EMP can cause alot of interfearence.
(2) Move the signal cables away from power cables for the same reason.
(3) Unplug your system from the mains and reseat the graphics card and reconnect/check all the cables.
(4) If your monitor has a de-gauss option use it to restore the display.
(5) Boot into the bios to see if the display is distorted there. If it is then it is hardware related and not software.
(6) If it is software related then reinstall the drivers
for the graphics card or restore to a time before this started to happen.
Let us know how it goes.