NO DISPLAY

if your computer still fine and boot normal only display is problem?
try use another monitor might be your monitor is the the problem
or
if you have extra video card try use it if work your video card need to replace or if you don't have video card buy new one

NOTE!
Remeber while opening your computer and touching always touch to a metal to discharge the static electricity in your hand ^_^

or Bring it to PC Repair Shop for more experice to do it for you