I recently bought a Trx450es and it ran great, I went riding one day and it seemed fine I parked the bike and went out the next day to start it, the bike fired right up but when you try and shift there is nothing, not even a click, I can still shift with the emergency shifter, I took the shift motor apart and seems good and I replaced the angle sensor and still nothing, all fuses are good, not sure what to check for next

 

Not even a click would indicate the ES system isn't getting a signal from the shift buttons, either the main ES fuse has gone, or possibly the wire from it to the ECU or shift buttons has broken. Other possibilities, the wires to the shift motor have a fault or the ECU has gone wrong.

 

The ECU shift computer relies on several sensors, as well as the wires and connectors. If you want to fix it quick and easy, you can bypass the ECU. I did that on both my 2000 Rancher and 2000 Foreman. They shift great now. Go to youtube and search for the how-to video by Bubba Baryl:
Honda Rancher Shift Problems - How it works - How to fix ALL PROBLEMS