If You Can Open Your Workbook

If you can open the offending workbook, before doing anything else, be sure to save a copy of it; otherwise, you might regret it. If you have a copy, you can always seek professional help!

Now, try opening the workbook in a later version of Excel and simply saving it again. Obviously this is not possible if you already are using the latest version of Excel.

If this doesn't work, try opening your workbook and saving the file in HTML or HTM format (see the "What You Lose in HTML or HTM in next section" sidebar for a warning about these formats), then close the file and reopen it, this time saving again in the format you require-e.g., .xlsx. Finally, try opening your file and saving it in SYLK (.slk, for symbolic link) format. Note that when you save a workbook in this format, only the active worksheet is saved. So, you will have to do the same for each worksheet. Reopen the file and save it in a desired format such as .xlsx.