so i was using my computer then the stuff on the monitor went distorted. nothing was wrong with the programmes. and then later it went blank. when i shut down and open i saw a grey screen. and distorted stripes. whats wrong?

Hard to tell - especially since you told us nothing about your system. The first thing you need to do is swap monitors with another computer. If the problem follows your monitor to the second computer, then you know the problem is with the monitor. If the 2nd monitor on your computer does the same thing, then you know the problem is with your computer or its graphics solution.