No I doubt if it is still alive - the branch that is - but you could still grow the tree and it might be a bit lopsided.

I've done it to the branch of a shrub, by taping it back on very tightly immediately after it got severed ... but it was alive and full of leaves at the time.
I don't suppose you've got anything to loose by trying it. If it doesn't take, the tree will grow new branches anyway.

I think if it was me I,d prune it cleanly to prevent disease, as it grows you could prune it into shape, although often you find another branch or shoot will grow to fill the gap

I snapped branches of a young acer a few years back. I tidied up the breaks and it made new stems further down. It's now beginning to form a nice shape again.
If your specimen is grafted (usually are) and the break is above the graft then you should have no problems.

As Hywel says, you can effect an immediate repair when you inadvertently break or cut off a branch you want by taping the parts back together, sometimes with a splint of sorts, maybe a bit of stick, and it works. But if the branch has been broken off a while, its not likely it will reattach itself, particularly at this time of year when the sap has dropped.

Thank you for your replies. Decided to not attempt surgery on the tree! The company were great, a replacement arrived 2 days later, well packed and I damaged.
The branch which broke off was the main one so I don't hold out much hope for it surviving.