Why won't Excel open a file from my flash drive?  It acts like it will, displaying, "Started...", and "Opening in Protected View," but it never opens.  I had Windows 8, updated to 8.1, and recently updated to Windows 10.  I have Office 2013, and even went into its settings to allow the program to open all files. 

• Moved by Edward ZMicrosoft contingent staff Friday, September 04, 2015 5:34 AM product related

Hi,

Regarding of the issue, please provide us more information to assist you better.

• Was this issue occurred with other Files? Such as Word document...
• Have you copied the file from flash drive to local disk and opened it?
• Have you changed a flash drive or USB port to test?

This issue might be caused by some factors, please try the following methods to narrow down it.

1) If you get the alert message "The file is corrupt and cannot be opened" when opening. Please try this:

File > Options -> Trust Center -> Trust Center settings -> Protected View.
Check all the options again under Protected View, click OK and restart Excel.

2) If the files can opened after copied to local disk , this might be due to anti-virus software or fire wall blocked, please disable them to test.

Please let me know the result after you testing.

Regards,

George Zhao
TechNet Community Support