Headphone Repair Question

The most common cause for headphone problems is one (or more) wire breaking just where the cable exits the jack plug. Did you cut the cable there?
Also, the jacks you get to buy these days are entirely made of plastic, so when you solder on them the plastic melts and you loose contact.

 

Measure the resistance between body and ring also body and tip. If there is no connection, that is the one to investigate. The phone will click from the voltmeter current if it is working.

 

Wihout a meter you make things difficult but if you have an assistant, you can get them to hold a couple of wires to a single cell and you can then flick these across the plug contacts to make a noise.
One technique that I have used is to try to pull the wire out of the cable with a pair of tweezers, if the wire comes out, you know where the break is.

 

Like Resqueline said, you've got a break somewhere in the wire. It's usually at one
end or the other of the cable, at the headphone, or at the plug. But it could be anywhere
along the length of the wire.
I've never run across a problem with the speaker itself, but it's possible, to check it if
you want to, run a couple wires from the working speaker to the non-working one, to
verify the speaker is ok. But like I said, odds are, you've got a break in the wire somewhere.

 

Try looking at the jacks socket solder connections to the pcb, as cracked solder joints here will also render one channel not working, your wiggling the plug about could surgest this, i had an old sony Walkman years ago now, i opened it up re tinned the 1/4 inch socket and my head phones where restored.