What year and make?
1999 ford explorer 4.0 manual transmission gear shifter wont fit on shaft
you most likely need a new clutch
it wont change gear properly. if at all,,, because of the oil thickness
most likely the clutch & pressure plate is shot.
If second is the only gear that does not work, there is an internal failure. The transmission will need repaired or replaced.
It is quite possible that your clutch is not disengaging the transmission from the motor. Also, your synchros could be bad, which would not allow it to go into gear.
Check if the clutch is working properly.
Sounds like a bad clutch or pressure plate
there are a few reasons why this can happen but the most likely is a problem with the slave cylinder
Gear up then
you either got air in the hydrolic clutch or the hydrolic clyinder is out .check your fluid level.
answer gottransmission.com rebuilt trans if your planning to keep your car,just search how to install then you gain years