while using facetime my screen crashed and won't reboot-screen opens in stripes

Right off the bat, sounds like a hardware issue to me, but try: Reset the System Management Controller (SMC) on your Mac - Apple Support.

If that does not help, it should probably be evaluated by Apple. You can set that up at http://getsupport.apple.com.

Try this: How to reset NVRAM on your Mac - Apple Support and this: Reset the System Management Controller (SMC) on your Mac - Apple Support and we keep the fingers crossed for you.