Question about software - Excel or Word?

To revise it you should find out where the file is open and get it closed. If you use save as you will have to give the file a new name and you will miss any changes made where the file was open when you got the message.

If you are on a LAN at work that means you are working on the file with others and need to coordinate with them.

If you are working at home the message means that you left the file open in another instance of Excel and could have changes there that you have not saved and will eventually if not almost immediately get confused about what work is where.

If you can't find the other instance on your home computer, save a backup copy of the workbook you opened and then use Task Manager to end every EXCEL process. The next time you open the workbook with either the old or new name you will be able to make revisions. It would be a good idea to reconcile the two workbooks and resolve them into one before going forward.

right click> open read only> open it> file menu> save as> save to your documents or your desktop