Minecraft Forums

This is for my son (I know so little about this stuff) - Minecraft was working fine. But now when he starts up and try to load a world he created, the screen that says "loading world/building terrain" comes up for about a minute with nothing happening, and then it goes back to the start page (where you pick single player, multiplayer, etc.). I had recently installed Norton on the computer, and I did read where that sometimes interferes, so I removed it, and still no change. I also updated Java. Still no progress.

Does anyone have any ideas other than reinstalling minecraft? And if the only possible solution is reinstalling, then how do I save his worlds? I know I have seen some directions on how to do this in other posts, but I am completely technologically inept, so need perfectly idiot-proof instructions.

Thanks in advance.