2004 Jetta VR6/manual transmission won't stay in gear
 

I own a 2004 Jetta VR6/manual and replaced the clutch last year. Several days ago, while driving, I could not get the car into 4th gear. I would shift into 4th but it would not engage. It then would not engage in any gear. Was wondering if anyone would have any suggestions as to what is causing this issue. Again, the clutch seems fine i.e., I can push in the clutch and it has good play but the car simply won't engage in any gear. Any ideas as to what might be the cause for this?