Hi Betty,
If Excel files won’t open, the most common causes are either file association issues, corrupted Office installation, or blocked add‑ins. First, confirm that the file type (.xlsx, .xls) is correctly associated with Excel by right‑clicking the file, choosing “Open with,” and setting Excel as the default. If the file still won’t open, repair Office from Control Panel → Programs and Features → Microsoft Office → Change → Quick Repair. Also check whether the file is stored on a network or OneDrive path with sync issues, as that can block opening.