If you have a laser printer, it is very likely to be postscript. In this case it will hold the text + images and can easilly be converted into something like PDF.
If you have an inkjet printer it is likely to be some proprietary format, but there may be tools to read it. If you only need an image file, let it print, then scan it
Yeah, I know that solution sucks quality-wise.
As for recovering the data in whatever format it's in, try looking in C:\WINDOWS\system32\spool . That's where the stuff it's saved, but I have no clue as to the format/structure of the queue.
One more thing which *might* work is changing the printer properties to print to FILE: instead of LPT/USB/COM. Not sure if it will affect jobs already in the spool, but if it does, it's your lucky day.