iMac won't start up

Help! For some reason our computer froze yesterday which is usually no big deal because all we have to do is turn it off and leave it alone for a while. We left it alone over night, this morning I turned it on and immediately noticed there was no noise coming from the speakers(they were left on) and then it wouldn't get past a grey screen with 3 white lines down the middle but after it's left on for a few seconds it starts to do this. I don't know why it's upside down but you get the idea. The cursor doesn't show up at all and have tried everything that was suggested for me to try. Is it possible that our graphics card went out as I have read from others with the same issues? Our computer is from either 2010 or 2011. Can't remember for sure. Any advice would be greatly appreciated, thanks.