I have a dev environment and recovery scripts set up that allow me to perform data recovery very quickly and thoroughly.
Corrupted files of most formats are often recoverable. Common ones are the Office suite formats (like .doc, .xls, .ppt, .pps, .pub, .accdb), including their x-suffixed brethren. PDFs and Compressed folders (.zip, .7z, .tar) can usually be recovered. Audio files (.wav, .mp3, .aax, .mpeg) can also be salvaged most of the time.
Sometimes, only a partial recovery will be possible. This is too bad, but hopefully it will save you much of the effort of rebuilding the lost file.
If the file size has dropped to something ridiculously low (e.g. 1kB), you may be out of luck. Don't send these files to me and expect miracles.
Single file data recovery attempt
I will use all the tricks in the book to quickly recover your data from corrupted files.
The $5 buys me a coffee. I drink a lot of coffee... In short, I know what it feels like to put my effort into something and have it go to waste, and I get a twang of satisfaction from putting in a little effort to save someone else a lot more trouble.
I can try. Send them to me anyway to take a look. I'll ransom them for the 5 bucks ;)