whys my chain saw not working?

Hello Mrs Clark
So, you've taken the side cover off to reveal the cutting bar complete with chain, you've taken the chain off the bar, and you are now left with the centrifugal clutch drum, complete with the sprocket that drives the chain. If this drum can't be turned, there's only two reasons, really:
1) The brake that stops the chain rotating is locked on (its the forward one of the two handles - not the one that you hold the saw with)...if this handle is pushed forward, a steel band grips the clutch drum, preventing it from turning. To release the brake, tug the handle smartly towards you and things should come free.
2) However, if you have done this and the thing still won't spin, it seems that the complete engine has locked up somehow...and it can't even be turned by the pull starter.

John
August 2009