A Key cap has fallen off. How do I refit it?

[hmuller]

I have the same problem with key "A" I can out bck in but it it a bit loose and pops out after a couple of presses.

Is the plastic hinge attached to the key cap when it pops off like OP? If so, you can attempt the suggested solution above. If not, I would encourage you to follow xalius's advice and open a support ticket.