Hyundai Repair: troubles in my hyundai elantra automatic gearbox, transmission control module tcm, hyundai elantra

Question
the gears are not changing sometimes even though i changed the speedsensors and the 2nd and 4th gears solenoids but no joy

Answer
Hi, Hamza.  There are a host of reasons why a transmission may not change gears.  I'm presuming it's stuck in 3rd gear, since this is the failsafe gear.  Let me know if it seems I've made an inaccurate presumption.

If you can answer the following questions, it'll help me determine where to steer you next.

1.  What year is your Elantra?
2.  Are there any diagnostic trouble codes (DTCs) stored in the transmission control module (TCM)?  If so, what are they?
3.  The transmission doesn't have a 2nd nor a 4th gear solenoid per se.  Can you give me some information regarding how you determined which solenoids to replace?  
4.  Why did you replace the speed sensors?  I'm presuming you've replaced the input and output sensors.