With something as important as "more than a year's worth of work", you surely saved a copy of those files to a DVD, or flash drive, or external drive.. Since we only lose what we don't back up, and hard drives don't last forever, you should have such a backup of those important files. Do you have such?

If you didn't make a backup of your important files, (some lessons are learned hard), have you tried doing a search on the computer for the file extension of the original files? It may be saved in a different location, possibly the "Temp" folders.

The message regarding "disk access failure" and the other symptoms you've mentioned are usually related to a failing hard drive. If you're currently unable to boot to Windows, or the files are worth a lot of time and money to you, the best option is to turn OFF the computer and take the hard drive to a hard drive recovery company.. The more times you add data to the drive, then more damage will be done to those files.

Hope this helps.