You may encounter an Excel worksheets that has merged cells that you don’t know about. This can be frustrating because Excel doesn't sort data in a column that contains merged cells.
Following the steps below, you can find all the merged cells in your worksheet and then unmerge those cells.
Click Home > Find & Select > Find.
Click Options > Format.
Click Alignment > Merge cells > OK.
Click Find All to see a list of all merged cells in your worksheet.
When you click an item in the list, Excel selects the merged cell in your worksheet. You can now unmerge the cells.