Well, you two are extremely intelligent! I believe I lost you both at "VB..." I'm a fast learner but have no idea what we are talking about here. Sorry~
Would either of you be able to dumb this down some, for me?
First off, my manual solution did not work for you because I had assumed you had data on multiple lines within the same cell and wanted a comma at the end of each line except the last one. That is also what my VB code solution (as well as j.dsouza's) did,
so forget that previously posted code. However, there is a VBA solution which I will give to you below along with instructions on how to implement it. First, the code...
Sub AddCommas()
Dim Addr As String
Addr = "A1:A" & Cells(Rows.Count, "A").End(xlUp).Row
Range(Addr) = Evaluate("IF(LEN(" & Addr & ")," & Addr & "&"","","""")")
End Sub
The above code assumes your data is in Column A and starts at Row 1 (see the bolded text above). If that is not the case, then change the values (the bolded text) to match your actual setup.
HOW TO INSTALL MACROs
If you are new to macros, they are easy to install and use. To install it, simply press ALT+F11 to go into the VB editor and, once there, click Insert/Module on its menu bar, then copy/paste the above code into the code window that just opened up. That's it....
you are done. To use the macro, go back to the worksheet with your data on it and press ALT+F8, select the macro name (AddCommas) from the list that appears and click the Run button. The macro will execute and perform the action(s) you asked for.