Unmerge the cells:
Highlight all cells by clicking the blank box at the intersection of the
column and row markers (The places labled 1,2,3 A,B,C etc along the sides).
Hit CTRL+1 and go to the alignment tab. Uncheck 'merge cells'.

The cells should now be unmerged, but this may have left blank spaces (no
data was deleted, these cells were 'hidden' by the merge and could not have
contained anything). Delete those blank spaces, taking care to not delete a
cell and shift the data without shifting the corresponding data in the same
way.

Your sort should now work properly.

" wrote:

I am working on a databse another person created. When I go to sort it
keeps telling me all merged cells must be the same size, how do I fix
this so that I can sort my data?