Car was operating perfectly, shifting through all gears. Suddenly shifting from 2nd to 3rd, it would not go into 3rd or any other gears after that. When the clutch is let out half-way I get a whining sound. With the clutch in I can move into all gears and it feels normal but will not go into gear.

The shifter has been checked and is in the specified position. The slave fluid has been changed and is not below its normal level.
The transmission seems to be stuck in neutral as the car can roll back and forth.

i need help to identify what’s gone wrong.

David