Your USB cable does not have a red wire but has a yellow?
This means you have a non standard USB wire, they are common enough and assuming the thing worked in the first place it will be fine to use here.
You do however have to figure out what wire goes to what pin, if you can see it then great but if not you have to find out. You will probably want to desolder anything you have already done or at least check it as nonstandard colours does not mean the colours that are the same as the standard colours will go to the same pins.
http://pinouts.ru/Slots/USB_pinout.shtml details what is what and the picture above tells the rest of the story.
Put your multimeter in continuity mode (it is the mode that sets of the buzzer when you touch the leads together,
http://www.ladyada.net/library/metertut/continuity.html has more) and test the wires accordingly. Though I assume you used volt meter as an alternative to multimeter (best to use multimeter unless you really do mean you want to measure Volts) Voltages mean nothing here.
If you can not get your leads/probes into one of the ends to measure continuity then get an old device you can probe and use that (or another USB lead you can gut that has proper wiring colours).
If your multimeter does not have a continuity mode (many cheap ones do not) then use the resistance mode instead. Anything that has a non infinite resistance means you have a connection.
