Hi Susan,
It appears that you might have accidentally introduced a merged cell into the range you are trying to sort. A merged cell would include more than one row or column, which makes the logic behind sorting fail. There's no logical way to tell the sort feature what do with a cell that spans more than one row or column.
My question to you is, do you intentionally have merged cells, or was this an accident?
There's an easy way to remove all merged cells from a worksheet. Click the Select All button in the upper left corner of the worksheet, then on the Home tab of the Ribbon, in the Alignment group choose Merge & Center > Unmerge Cells. Otherwise, select the range you want to remove merged cells from and use Unmerge Cells.