Cannot put transmission in gear

If this was the issue before you replaced the clutch then there is most likely an issue with the synchronizers inside the transmission. However, it is more likely if the vehicle will not go into any gear that the issue is with the clutch still. Here are some guides that will help with what we need to do in order to confirm this:

https://www.2carpros.com/articles/clutch-symptoms

https://youtu.be/6N6b5F2ChyE

https://www.2carpros.com/articles/clutch-doesnt-work-sometimes-or-not-at-all

The reason it is not likely to be the synchro is because there is one for each gear. Meaning when you put it in first that is a different part of the synchro then for second and a completely different one for the other gears. So if all gears are affected then the clutch is not disengaging.

However, if it is just first gear then you could have a synchro issue.

Let us know what you find with this and we can go from there. Thanks