May, oddly enough this is the big toe that I haven't injured. I broke my left big toe about 10 years ago and the nail on that toe grows just fine, although the toe itself doesn't bend well anymore. The right big toenail is the one that isn't growing.
Stratford, I do recall a thread like that, although I think it was mostly about fingernails and not toenails. There were a couple actually now that I think about it - one about clubbing of the fingernails, and another about ridges in the nails - that vertical ridges are okay and normal but horizontal ridges can indicate nutritional deficiencies. I have totally normal fingernails with no clubbing and only vertical ridges, but my big toenails do get horizontal ridges. So maybe the nail not growing could be related to nutritional deficiency? Although I'm pretty much in remission right now and seem to be absorbing nutrients just fine nowadays.
David, I'm not sure if it's a fungus or if it's related to my gut illness, but I guess it wouldn't hurt to treat it like a fungus and see if that helps. That link you posted led me to several others, and from those I gleaned that vicks vapor-rub might work just as well as prescription creams on toe fungus, so I'm going to give that a shot. It looks like you just rub on a bit of vicks twice daily on the nail and surrounding skin. That seems easy and hopefully will work!