Idiots who don't note where the wires were! UPDATE!

[333rocky333]

They work because the toilet is likely the last light, meaning 1 cable is likely the Permanent Live in and the Neutral, 1 cable is to the switch L and SL, the 3rd cable as you know is likely the fan cable.
Why are they all parted?
A picture of it all connected would have been more helpfull.
If you have no power at the supply cable, then the fault could be between there and the next room, however this is unlikely to fail due to you disconnecting the fan, are you sure your not holding something back, a short circuit is usually the reason a connection blows further back. when nothings been touched.

 

[333rocky333]

Ps, they would need 4 connectors not 3, you need L,N,E and SL
I take it you checked the bulbs were ok in the light before you meddled with it

 

[charliegolf]

Meddling- harsh but true- yes the lamps were all ok. No, I have fessed up good and proper. With a 4 way block (I do realise it needs 4 now) can you say what I need in each of the four terminals opposite the neutral, earth and live wires on the lamp side please? Ta.

 

[JohnD]

test each wire to each other wire (at AC volts, around 250v) and list the voltages between them. Including the "earth" wire.

(1) with the light switched off

(2) with the light switchen on.

did you do that?

 

[charliegolf]

No, but I have a multimeter available. What am I looking for, and how will I use what I see? Thanks

 

[charliegolf]

I can make sense of this. But mine has a fourth conductor on one cable. Where would it go?

 

[333rocky333]

https://www.diynot.com/wiki/Electrics:fan

 

[JohnD]

No, but I have a multimeter available. What am I looking for, and how will I use what I see? Thanks

When we see the results it will probably become clear.

 

[EFLImpudence]