Excel cannot open the file because the file format or file extension is not valid

I have big problem. I transfer data (excel file and word file) from my desktop computer to external HD but when I transferred the files they locked. I can not open them and I can copy from external HD again to mu computer. When I try to open I got error

**cannot open the file because the file format or file extension is not valid**

I try this link https://www.easeus.com/file-recovery/excel-cannot-open-the-file.html#:~:text=Error%20%22Excel%20Cannot%20Open%20the,File%20Extinction%20Is%20Not%20Valid%22&text=Verify%20that%20the%20file%20has,has%20come%20corrupt%20or%20damaged.

but I don't have option copy, export... everthing is disabled.

Also when I Right click file, which is locked on external HD, I had File ownership -> Personal I got error:

Error Code 0x80071771 The specified file could not be decrypted

Can anyone help me? Thanks...