If the Sorry, Excel cannot open two workbooks with the same name at the same time error is preventing you from using Excel, see this post.

For some listings, no Save check box appears. Microsoft Excel can open these file types but can't save documents in these formats.

Can’t type numbers or enter data into Excel cell The troubleshooting guidelines to deal with this problem are explained below. But before you proceed, close all the Excel files and open Excel again.

Numbers has the ability to open Excel files so you can work on them. You can also export spreadsheets in Numbers so that they are compatible with Excel.