Hello and thank you for choosing Just Answer.
Is the handle hard to move or it just won't go into gear?
So it's the shifter that you are having trouble moving?
Will the shifter move left/right in neutral?
Is it hard to move it left/right in neutral (not trying to get it into gear)?
(I am very sorry about all the questions, I'm just trying to give accurate diagnostic.)
Do you ever hear a grinding noise when you are putting the car into gear?
If there is no grinding, then the clutch is being disengaged properly. This is not a clutch fluid system problem.
To me it sounds like a shifter assembly issue. Most likely you will need to have the whole shifter assembly replaced.