I can't load runescape after I choose a world, and its really frustrating:(

Is it showing a blank screen, or is it giving you an error message with it. I cannot help you with the error message, but I can help you with the blank screen. Just go here (http://macromedia.com/downloads), and download macromedia flash player. Then it should work.

If that still won't work just change the Java application. You can find that at the bottom of the detail screen.