Files will not open. New icon

New icons on a lot of files. These will not open.
The gold thing bottom left.
Can anyone help
Dave

Certainly no Excel expert here, I know just enough of it to get myself in trouble ... LoL

Just doing a reverse image lookup of the image you provided came up with this ....

"In your OneDrive folder, a file icon with a file box icon appears in the lower-left corner.
Is your operating system Windows 11?
This icon indicates a sync failure in OneDrive on Windows 11, indicating that the file cannot be synced.
If you need to "resolve" this issue, try manually syncing. If syncing still fails, it may be due to network issues. You can try modifying your current network settings:

1. Right-click the Start icon and select "Command Prompt (Admin)." In the command prompt, enter "netsh winsock reset" and press Enter.

2. After successfully resetting the Winsock directory, restart your computer to complete the reset. Right-click "Network" and select Properties. In "Network and Sharing Center," select Change adapter settings.

3. In Network Center, right-click "WLAN" and select Properties. Select the IP4 protocol.

4. In IP protocol settings, set DNS to Manual selection.5. Enter 4.2.2.1 or 8.8.8.8 for the Primary DNS and 4.2.2.2 for the Secondary DNS, then click "OK.""

If I was guessing , and I am, I would say you have probably in some way messed with Onedrive. (maybe you tried to get rid of it and didn't do it correctly).
NOTE: You can not arbitrarily just uninstall onedrive. Other steps have to be done first.

If you do not have Microsoft Office 365 (1 TB OneDrive storage space included with 365)
You have probably run out of the 5 GB space on your OneDrive.
Browse to C:\Users\UserName\OneDrive.
Turn off Automatic Syncing of OneDrive

Without more info from the OP as to what he might have done regarding Onedrive and whether or not he wants to use Onedrive, what has been suggested is not a full solution. The solveyourtech link does not mention everything that must be done if the user does not want to use onedrive. The correct procedure has been mentioned time and time again here. Depending on the OPs state, if not done correctly he can end up in a mess..

Thanks everyone for your input/help. I have reinstalled onedrive and now all is well.
Thanks again
Dave

Dave, is it your wish to not have your files synced to onedrive? If so I will provide you instructions.

See What are these Brown Box Icons in left bottom corner of my files?

And Brown box on Desktop icons