What is wrong with my white knight model CL447WV?

I am hoping someone can help me figure out what is wrong with my dryer and how do I fix it! It was working completely fine one minute then when I turned the dial to put it back on it didn't spin.

It sounds like the electrics are working though as there is a slight whirring sound but nothing happens with the drum. I tried to take the back off then decided to stop once I got down to the last three big screws in the middle.

With three young children I desperately need the dryer back up and running!

Thanks