If you have the exact file name, it's helpful to put it in quotes. If you don't recall the exact file name, I agree with Rajesh that providing context about the file and should help the copilot find it. Generally, copilot should have consistent behavior between "x file" and "please find x file". Thanks for calling out that you are running into this issue. I will add this type of behavior to our test set so that we can improve the copilot in the future.

You can try adding the name of the person who shared, medium in which it is shared like chat, email or from Sharepoint, if you remember the date you can mention that too or if it has any keyword like project name or customer name you can add that too. Basically play around the prompts until you are able to get the expected output.