Problem with light fitting

[Shaolin]

I have a ceiling light fitting that stopped working. It turns out there's a loose wire that has come adrift of its fixing. The problem is that there are two places for it to possibly go and no indication at all of which one it should go to. Any ideas? If I just try and hope for the best, what's the worst that could happen - a blown fuse, so fix fuse, change the wire to the other place and it's all ok? or worse?

The yellow tape is covering the loose (black) wire in the pic, there are three reds together at the back and in the two terminals at the front one black wire each, the errant black should be joining one of the two blacks, but which one? There's not a loose screw to indicate so I guess it was never fixed properly in the first place.

[Ferg]

One terminal will have two neutrals, one terminal will have two lives..these are the ring. In with the two lives will be a third wire which goes to the switch and returns up the black so it's a LIVE, but coloured BLACK. This will go to a terminal on it's own connected to the pin of the bayonet fixing. SO...it sounds like the BLACK from the switch is still connected.
You need to put that 'floating' black in the terminal that ISN'T connected to the pin of the bayonet.

[Shaolin]

Thanks for the reply - I only had 3 black wires and in the end thought I'd risk putting the loose one into the terminal it was closest to. Lo and behold it all worked fine, I thought the worst was a blown fuse and a lesson learned.