Today I somehow accidentally deleted some source code files in Intellij IDEA. I don't know how this exactly happened - I must have clicked the wrong menu item.
Because I'm using Git for version control I could recover the files immediately (see below).
To show deleted files use the command:
"git ls-files -d"
To restore the deleted files use:
"git ls-files -d | xargs git checkout --"
(without the quotation marks of course).
The source for this information can be found here:
So, thanks Git!