Speedometer not working, heard a noise from front wheel hub a few miles before, attached cable at hub, detached at top and when the wheel is spun the cable does not spin. Please advise.

The moment you can hear a loud noise coming from front wheels while driving straight that means that your wheel bearings are ready for replacement. In a Mazda 323 BJ (1999-2004) it usually comes every 150-200 thousand kilometers (95-120k miles). To replace the bearing (do two of them in one go even if only one can be heard) you need to do as follows:
Loosen the nut on the half shaft, jack up the car, remove the wheel, dismantle brake caliper and brake disc, remove all ball joints attached to the hub, detach the shock absorber from the hub (no need of removing it completely), once you have the hub basically hanging on the half shaft, untie the nut and pull the hub out of the shaft so you can hold it in your hands. You will need to go to a garage with a 12ton (minimum) press, no point of trying to hammer the bearing out as you may damage the hub and your whole work will be for nothing. Get the old bearing pressed out and the new one pressed in.The Mazda part numbers for the front bearing kit are: B455-33-047A(B,D),GJ21-33-042B,G304-33-065,B21M-33-048.
After getting the bearing fitted into the hub, all we need is to reverse the whole process, put the shaft into the hub, attached the hub to the shock absorber (makes it easier to attach the rest), put the nut and tight it just as much to feel there is nearly no movement (do not overtight it as this might damage the bearing), attach all ball joints back to the hub. Make sure all nuts are tight, use a tension wrench when needed, put the brake disc back on the hub, install the brake caliper, once you have all them on and tight put on the wheel, then get someone to press the brake while you tight the shaft nut with the tension wrench, check the wheel for play or hard movement. Lower the car down and take a slow drive around (do not accelerate sharply or brake rapidly, just a gentle drive around. Normally a wheel bearing should be in correct position and use after about 200km (120 miles) distance. After that check if it is not overheating (too tight) or there is a play (too loose). Tight or untight if necessary, recheck after same 200km (120 miles).