Say your text is in column A and columns C and D are empty.
In C1 enter ".JPG" without the quotes.
In D1 enter =A1&$C$1
Copy this down as far as needed. You can then select Column D and paste
special values over column A before deleting Columns C and D.

Alternately you could use a macro. Select all the cells you want to
change and the run this:

Sub addjpg()
Dim cell As Range
For Each cell In Selection
If Not cell.HasFormula Then
cell.Value = cell.Value & ".JPG"
End If
Next cell
End Sub

Save your work before trying either option.

Hope this helps
Rowan

bweiner wrote:
I need to add the same text (.JPG) to existing text. I have over 4000
existing cells to add this same file extension to. I can't seem to figure
out how to do this without manually going into each cell.

Any suggestions would be great.