Verify that the file is not corrupted

Hi guys, I have an issue here regarding my XLS file.
I downloaded from the internet a data sheet that I needed most.
When I opened it with Microsoft Excel it cannot be opened instead it displayed an error message.

Microsoft Excel
The File you are trying to open, UNCFORMS%200N%20MAND.xls’. Is in a different format then specified by the file extension Verify that the file is not corrupted and is form a trusted source before opening the file. Do you want to open the file now?
Yes No Help
I pasted above the error message for your reference of my problem.
When I analyzed the error above, it seems that the file is corrupted, that is why I decided to download again another copy of the file.
But when I opened it, same problem occurred.
Please help me look for some solution to my problem.
Hoping to hear from you soon.
Thanks.
