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Do you have a backup of your work?  If you restore from last week's backup can you open the files OK?

Do you have a second PC that you could try opening one of the problem images with?  How about uploading an example image to http://www.ee-stuff.com/ if not - let's see if we can pin the problem on the files or your PC.

Sounds like your images may be corrupted. Beyond anything we suggest here, you need to explore the reason why they are corrupted (virus, failing hard drive, etc).

* For the following items, always work on COPIES, not on your originals. If you have reason to think your HD might be failing or causing the corruption, don't install new programs on the computer until you've copied anything of value off of that computer *

Here's some thoughts for you: First of all, try photo recovery software... take a look at PixRecovery (http://www.officerecovery.com/pixrecovery/) or BadCopy Pro (http://www.jufsoft.com/badcopy/) or PhotoRescue (www.datarescue.com - for both Microsoft Windows and Mac OS X). Each of these can deal with corrupted graphics files, and help repair the damaged files. I've had my best success with PhotoRescue, although sometimes images can be fixed in one of these and not the other. Typically these come with trial versions which will let you know if you will be able to recover any images.

You can also sometimes open corrupted file in applications like CorelDraw (which can sometimes import damaged JPGs. Once the file is imported into Draw it can be exported again as a new fresh JPG) or Photoshop (using RAW mode). For the latter, you need to know the size of the image in pixels. What you do in Photoshop is select File>Open As and in the dialog box choose RAW and then the file you want to open. Another dialog box will ask you to enter a size in pixels and the amount of channels (choose 3 here), leave the Header Size blank and click OK.

You might also try opening the file (even if it comes up black) and re-saving it in tif format. Save it as-is as soon as you open, then exit Photoshop and then re-open the new .tif file. You can also try rotating and saving, etc. Make sure you don't save over your original.

Last, some times the file can be opened in a text editor or a Hex editor, and the data stream altered slightly, allowing them to be opened with a graphics program. However, if there is a lot of information missing from the files, it is impossible to fully recover the images. The basic procedure is something like the following:

Open a working image files from the same source (same digital camera, etc.) as your corrupted files in a hex editor, and take a look at the flow of the files -  typically they should begin with FFD8, followed by a string of other characters. Get an idea of the flow.

Then, open your corrupt file, and look through the file. You're looking for a place where there's an obvious change to the flow of the data. If you can spot it, you might be able to fix it - at least if the damage is obvious, like a erroneous character or blank line introduced into the file.

Not to nag or say "I told you so", but ALWAYS have a backup plan and use it - recovering one lost file, like this, can make it worthwhile.

Hope that helps,
LHerrou