Hi @Ansuman Dutta Pal
Is there any image in this Excel file?
Please back it up first, then remove the image to have a check.
If needed, you may try to click Insert - Images (from file) to insert the image back.
Besides, I suggest you copy all content to another workbook to check the outcome.
If the steps do not work, here is a similar thread, please refer to dlauzon's suggestion, check if there is a couple of bogus tags in an embedded text file, and remove them.
Excel Worksheet and backups suddenly get Unreadable Content Message
Hope the information could be helpful.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.