Small Engines (Lawn Mowers, etc.): Craftsman LT100 wont engage, lt100, full speed

Question
Mower worked fine two weeks ago; finished mowing and then put it in storage.  Started it this morning and it runs great but won't 'engage' when applying the throttle.  It acts like something is blocking it from going into gear or moving.

Answer
Does the engine run full speed?  Does the engine idle?  Will the blades engage or turn?

I need the model number off the sticker.  The model number will be a format similar to xxx.xxxxxxx.

With the engine off, can you shift gears?

Send me the model so I can look up some information.
Eric