As you have discovered, you can't run PPC programs such as AppleWorks on Mountain Lion. I assume your Mac previously had 10.6.8 on it: if so you can deal with this by buying an external hard disk and installing Snow Leopard on it from your install disks. Then you can start up from it and run AppleWorks.
Alternatively, success has been reported in running Snow Leopard under emulation in Parallels - the method is described here: it seems complex; however Snow Leopard Server is available in the Apple Store (by telephone) at a reduced price (the last time I checked) and this makes the process a lot easier. I haven't tried either method: use at your own discretion. You can then run AppleWorks as an emergency measure.
However depending on the file types you can open certain of them in programs which will run on Mountain Lion:
- Word Processing documents can be opened directly only in Pages (AppleWorks 6 only).
- Draw Documents can be opened directly only in EazyDraw (the more expensive version from their website, not the cheaper one from the Mac App Store, and you will need v4.0 'Retro' not the most recent version) or Intaglio (though this appears not to be able to handle very complex drawings).
- Spreadsheets can be opened directly only in Numbers.
- Presentations can be opened directly only in Keynote.
Unfortunately nothing whatever will open Databases or Paint documents.
Some more details in this article: