And, as a diagnostic test, use a simple command
as the thing you either type or paste in, then hit enter. DIR has been a valid Windows command for as long as windows has existed. And if you've opened Command Prompt with admin privileges, and are sitting in C:\Windows\system32 you will get a long stream of results from the DIR command.
Command prompt is not case sensitive.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
Always remember others may hate you but those who hate you don't win unless you hate them. And then you destroy yourself.
~ Richard M. Nixon