To fix the “Excel file format and extension don’t match” error, first check if the file extension matches its format. Try renaming the file with the correct extension (e.g., .xlsx for Excel ...

This won’t fix corrupted files, so ensure you identify the right extension. Open File Explorer and click on the View tab at the top. Make sure the box for File Name Extensions is checked. Once file ...

For example, if a file has been saved as an Excel spreadsheet, but it has been given the “.txt” extension, it means that the file has been saved as a text file instead of an Excel spreadsheet. This ...

If the DAT file you're trying to open is text, you can convert the file into text in the Microsoft Excel program by first saving it as a CSV file. Right-click the DAT file on your PC and click "Open." ...

First try to rename file. Go to tools, folder options, file types and check have you .xlsx extension. If not then rename the file .xlsx to .xls. Second try to use excel command in file menu – Open and ...