Transmission not going into gear when engine on
So I have an na Miata with 150k miles. The previous owner garage kept it (so I was told). I’ve had it for almost 2 months, it just arose. Earlier today I drove the car from work and it was perfectly fine, the drive was two hours. I turned the car on, put down the e brake, press the clutch and the shift nob didn’t want to go into any gear whatsoever. It completely works fine when the engine is off however. I turned it off started in first and got going. When I was driving, the only way I was able to switch gears was by pushing it into gear with considerable force. Help would be much appreciated on what to do to make it running properly and smoothly again. Thank you!