Transmission will not shift into gear

My car will not shift into overdrive.

I have a 99 mercury sable. When I initially start it, it will not shift out of 1st gear. If I restart the car, it will work just fine after that. It happens every time I go to use my car in the morning.

My transmission seems to change out just fine with the exception of the hard shift from first to second. The other two shifts are a little hard but not as much.

I did scan it and it has a p1764 code.

Hi

While I was driving on the highway in cruise control set at 60 the car suddenly started to decelerate. I coasted off the road and noticed the car would not go into gear. I have not had any previous problems with the transmission nor any slippage. What are some things that would cause this failure.