Make sure there is no crud around the exposed joint. if it hasn't fully come out The get a hard bit of wood offcut big enough to hold safely.get a lump hammer or copper faced mallet put the wood over the hub area where the hub nut goes and give it a good wack don't go mad with it a few hits and it will pop in
They're pretty resilient, the worst that can happen is the shaft comes out of the joint and the ball bearings come out, which isn't difficult to reassemble. Push it back in the box by hand aligning the splines, and just gently knock it back in on the outside of the CV joint.
1998 Mazda RX7 FD Type R Bathurst 1990 Toyota MR2 AW11 2005 BMW 320d 1992 Vauxhall Astra GSi 1993 Vauxhall Astra GSi C20LET