Show hidden files

Hi,

I think I might have hidden all the image files I had in a folder by accidentally pressing a combination of keys.

Repro steps:

1. Image files in a folder

2. Press some keys

3. Image files suddenly disappear (folder still visible)

The files are not in the Trash.

I've googled how to show hidden files (in the Terminal) but the commands I found don't work for me. Any thoughts?

Thanks!

MacBook Pro (13-inch, Late 2016, Two Thunderbolt 3 ports)

Mac OS Sierra 10.12.2