No need to take offense, but I think the pictorial to which you linked specifically addresses issues where the speedometer proper works, but something is amiss in the hardware to drive the odometer and/or trip odometer. That's a fine procedure to know, and I've done a similar one msyelf. I don't see, though, how that can possibly solve his problem if the speedometer itself is not functioning. If I'm misunderstanding something about this, then please, let me know so that I'll be better informed!

I think Ken in NC has already suggested the first thing I'd suspect - the drive cable.

If everything up to the speedometer were OK, then I'd check the speedometer itself. I don't know anything about fixing the innards of the speedo proper; if it were broken, I'd probably be resetting the odometer on a spare unit and installing it as a replacement. After that, maybe some research here to see if there were anything to be done on a DIY basis to fix the sick one. If that came up dry, I might end up taking the sick one apart for my own edification and amusement.