Chevrolet Repair: 97 Blazer transmission, reputable shop, slim chance

Question
I have a 97 Blazer, 4wd,automatic.  The I had just driven about 10 miles one morning, stopped, shut it off for 15 minutes, started it up and took off. I now had to "coax" it to shift into 2nd, it doesn't shift into 4th (overdrive?), and reverse is gone.  What would cause all of these symptoms at once? Two shops have told me (without seeing the vehicle) "It needs rebuilt". I had no problems with the trans. prior to this sudden event. Is it possible that there is a single, simple problem here? Thank you so much in advance.

Answer
No the odds are slim to none that there is a simple problem that will fix the problem.  Take it to a reputable shop and on the slim chance it is something simple hopefully they will be honest and tell you.  But yes it does sound like your reverse carrier broke in the trans and is a major job to repair.