if he cant fix the busted cable or go to a bike shop he can just set the chain on the most comfortable gear (read comfortable not easiest) and run the bike as a single speed. i commuted for years in seattle with only a single speed the hills are tough but doable. ive recently purchased anothe single speed bike and will be riding that as much as my geared bikes this winter.
good luck to him
OK. It sounds from his brief description that he has broken a cable. Unless he is savvy enough to affect a repair to that cable -- he needs a bike shop (that he states isn't available) at least to get a new part. If he can even find a good automotive mechanic, he could get the cable spliced and on his way. It won't be 100% but he can ride it.
There is an outside chance that the cable slipped out of the retaining bolt on the rear derailleur. If that is the case, he should be able to reinsert it, tighten it, and adjust it with common tools. If he has computer access go here:
http://www.parktool.com/repair/byregion.asp?catid=53