You need to seek professional help with this. You have a serious transmission problem when you loose only one gear.
your trans axle has nothing to do with you losing 2nd gear
If it's only when you attempt third gear the problem is in your transmission.
synchro second and third gear, not first gear
just third gear most likely trans damaged could be dragging clutch if in other gears also
take the tranny out and get it rebuilt by a pro i have to do it to mine i lost every gear but 1st.....
Automatic or manual trans? What am I missing here? Explain! If it is stuck in 3rd gear then it is obvious that it can't go in reverse.
IF the speedometer is not working it is because the computer is note getting a signal from the trans. and will not tell it to shift. Try replacing the speedometer the sensor in the tail shaft of the trans.
You need to have it checked. If it is in 3rd gear at stop signs, you are doing damage to the trans, by making it work harder to get moving.
Be sure the trans is full with the proper lubricant.
Trans looks like it is bad in 2001 Hyundai plantar,liquid in garage floor.Can it be from lack of gear oil I changed axle and lost some fluid
Guessing that the power to the transmission module is lost. Some manufacturers make available a "limp home" mode that reverts to third gear take off if the electronics are lost. In other words, if you unplug the computer harness from the transmission, the transmission will remain in 3rd gear so you can drive it to a repair shop.
check fuses check for 12v supply at transmission-- wire @ 12 oclock on trans connector