By mistake I pressed on "don't show this again". How can I make vscode show that option again?
There is a setting that enables/disables that message:
Workbench > Editor > Untitled: Hint
By selecting "Don't show again" you disabled that setting (setting it to hidden).
To get the message back, reenable it - set it to text.
ctrl + shift + PYou will get menu with all the languages.
Additionally you can save the file with correct extension to get all the language support installed in your VS code.
Hope this helped