Excel won't insert a column or row with this specific error message. In this case, Excel thinks that every column or row contains at least one item, so when you try and insert the column/ row, Excel would need to drop the last row or column which may contain valuable data.
Microsoft Excel can't insert new cells because it would push non-empty cells off the end of the worksheet". These cells might appear empty but have blank values, some formatting, or a formula. Delete enough rows or columns to make room for what you want to insert and then try again."
To insert a single column: Right-click the whole column to the right of where you want to add the new column, and then select Insert Columns. To insert multiple columns: Select the same number of columns to the right of where you want to add new ones. Right-click the selection, and then select Insert Columns.
Hold down CONTROL, click the selected cells, then on the pop-up menu, click Insert. On the Insert menu, select whether to shift the selected cells down or to the right of the newly inserted cells.
If the worksheet contains frozen panes, you will not be able to add rows in the Excel sheet. Last but not the least, if the workbook is protected for safety reasons, Excel will not let you edit the sheet which ends up in several issues.
You can unlock/unprotect an Excel sheet without a password if you have a Google Drive account. To create a new Google Drive document, open your account and click the 'New' button at the top-left corner.
Press Ctrl + 1 to open the Format Cells dialog (or right-click any of the selected cells and choose Format Cells from the context menu). In the Format Cells dialog, switch to the Protection tab, uncheck the Locked option, and click OK.
Go to File > Word Option > Advanced. Uncheck the Use the Insert key to control overtype mode option under the Editing options.
Press the "Ins" key to toggle overtype mode off. Depending on your keyboard model, this key may also be labeled "Insert." If you simply want to disable overtype mode but keep the ability to toggle it back on, you are done.