glitched out my world and will no longer let me on minecraft

I can no longer play on my world or minecraft as it glitched when i put it on pause and when i went back to it after a couple of minutes it flicked in and out of the game and pause screen at high speeds. i then had to reboot my computer after the mouse wouldnt move on my screen to find my world had been deleted. i went out of minecraft and back on to find my start screen ould do the same thing: as soon as i press singleplayer it flicks me back to the start screen.