It seems you may have a corrupted workbook. Open and repair "MIGHT" get you to a better position. Worth trying but make sure you use a copy for a backup just in case.
Close and shut down your machine using the SHIFT+SHUT DOWN option.
When the machine restarts, ONLY open MS-Excel, and then ONLY open the copy of the workbook in question. Let MS-Excel try and repair the workbook, and AFTER the workbook is "repaired" SAVE this repaired workbook WITH A NEW NAME in a NEW LOCATION, preferably a local drive. Then redo the shut down with the SHIFT+SHUT DOWN option and then ONLY open MS-Excel, and then ONLY open the repaired workbook. If all is GOOD save it locally with the name you want and MAKE COPIES!