Dog acting crazy

Question
My Jack Russell just decided all of a sudden that he doesn't want to go up the stairs anymore. He acts as if he's afraid. Can't figure this one out... Help

Answer
How old is he?  Puppies go through fear stages about 4 months and 8 months.  If he is older, he may have fallen.  It never hurts to see the vet about unexpected behavior changes.  

Try not to push him too hard, carry him if you have to.  Show a happy, positive attitude toward the steps.  Don't tense up over it, that will only confirm his fear is justified if you are scared too.