How to fix my 51 plate transit 300 fwd?

I have just changed the clutch on my 51 plate transit 300 front wheel drive, I took it for a test drive all ok gearbox was a bit noisy. Today I can select any gear but my vehicle doesn't move I can change gear without the clutch. and I have noticed that the gearbox is leaking it's oil from the input shaft of the gearbox, is this a problem with the clutch or the gearbox