Can someone please advise me on what to do with mixed up wiring on ceiling light job?

I'm putting up a new light fixture, but I've got three black wires and the red band has fallen off the live wire. How can I tell which one is the live wire now?Can someone please advise me on what to do with mixed up wiring on ceiling light job?
Firstly i assume you are in the UK.





You will need a continuity tester, and make sure the power is off.





Connect the tester between a red and black from the same cable you should get a beep (all the cables may do this do not panic). Now ask someone to turn the light switch off. do this for all cables the one that bleeps on and off is the cable you require.





Put some tape on it for future reference.Can someone please advise me on what to do with mixed up wiring on ceiling light job?
How gan you tell? With a tester. Don't be afraid of electricity, just respect it's space. More Info would have been helpful. Pictures would be great, however since we don't: the only wires that you really needed to be concerned with are the wires that went to the old fixture. The wires that are (were) tucked up into the box should have been left alone. Let me know if I can be anymore help. Good luck
Call a qualified professional electrician before you get hurt or cause a fire that may kill you or your family. They have the tools and the experience to do the work in a safe and competent manner. The fees are minimal compared to rebuilding your home or a funeral.
gee pick 1 turn on the power and try it...
Use a mains tester.