Radio not working

CORRECTION. RED wire is normally which is what turns it on and off YELLOW wire is the memory wire from the battery. Would be surprised if radio and cig lighter are on the same one Otherwise it could be an earth wire come loose if you have power on the yellow radio should retain station settings. If red has no power it could be a fuse.
Some brands have those two reversed but not usually.

Would need alot more info what type of radio brand etc

I am yet to find a radio that requires a wire for memory purposes and unlike computer they don't have a clock involved.

All tait gme vertex simoco I have handled in past only needed two wires power and earth, whoich should be a battery not chassis earth

All the latest radios have two +12V inputs. One should be permanent which keeps all the preset channels in the radio. This one uses very little power. The other is to turn on the radio. I am pretty sure that most vehicles have the radio and cig lighter on the same fuse. If you are positive that the fuse is OK (measured with a multimeter) then you will have to check wiring from the fuse to the radio / cig lighter which will probably be a connector behind the dash.

What Wayne said is about right.

The clue is that the cigarette lighter power packed it in at the same time. It could be more so be wary.

Maybe something has penetrated or partly broken the loom somewhere (that's bad news). Or it could be a loose connection at the back of the fuse box (better news).

Has anything else failed?

Measure the resistance between one end and the other (fuse socket to cigarette lighter or radio). It should read a short or very low resistance between the two ends.

An open circuit or high resistance means that the wire is broken, or a connector is loose etc. But it won't show where so you would need to chase it to see why it broke.

If you can't see it or don't find a loose connector etc, then I would suggest that you take it to an autoelectrician there may be something worse going on.

Phil

Check the earth wires for a start If you have power on the yellow and it wont go ,thats the logical place to start

Maybe buy a Haynes or Gregories manual and trace the circuit?

Hi
Yellow wire is to constant power for clock, station presets etc. Red will be power via ACC on ignition. If its an aftermarket radio it sounds like its tapped into Cig circuit and may have an inline fuse stuffed behind dash somewhere.

Cheers

In some vehicles the accessory power is switched via a relay, check the main fuse box in the engine for said relay, it may be faulty.