Several years ago I wrote a short game in Inform 7, which was subsequently lost in a hard disk crash. I believed it was gone for good until recently when I stumbled across a copy of the Z-code file for the game on an old flash drive. Now I’d like to revise and expand the game, something which would be difficult to do without the original source file. Is there any kind of utility available that allows one to view or extract resources from compiled z-code files, or to decompile them back into Inform source code files?
The best you can get is probably Uninform. It produces Inform6 code. See ifarchive.org/indexes/if-arc … tools.html
And the I6 code is messy and doesn’t always compile right. I’d recommend opening it in Rezrov and using the “spiel” utility to get all the text, then rebuilding the rest from scratch.
TXD (in ifarchive.org/indexes/if-archive … tools.html) is another tool that will extract the text. There are several.
Thanks for the help everyone! Extracting the text will get me most of what I need, and has already solved some of the problems I had.
On a side note, don’t you think it’s a little bit embarrassing when you go back years later and play a game you wrote, only to realize that you can’t for the life of you remember the solution for a certain puzzle that you had designed in the first place? 
I’ve done the same thing in a more general way: Come back to some code I wrote years ago and wonder what in blue blazes I was thinking.