How to rename file extension on a windows phone (Lumia 620)

[Windows Central Question]

I often get emails on my Lumia 620 with extensions .prn, .nak, .out, .ack etc. These are not recognized by the phone & hence can't open them.

On my blackberry, I simply download & rename the extensions & it works. But on the Lumia, when I go to downloads, it shows that space is occupied by some files, but I cant see the files.

Is there a way to see the file names & change the extensions?

 

[xandros9]

Can you see the files under Files (Windows Phone 8.1) or File Explorer? (Windows 10 Mobile)