The Windows "Open With" dialog box will help you quickly reassign a default program for your Excel documents.

How to Open an XLS File in Excel. XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save ...

Q. When I open Excel, I always have to choose Blank workbook. Is there any way to have Excel do this automatically and skip the step of getting the Start screen? Q. I have a folder of Excel files that ...

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

If Word or Excel hyperlinks are slow to open, under usual circumstances or when they point to Microsoft AD FS Server, see this post.

Don't manually re-enter data you find on the Web. Open Excel and transfer the data directly into a worksheet.