auto-indent in emacs

[Kenneth Brun Nielsen]

I want to auto-indent a section (actually a whole file) in Emacs.

I googled, that the shortcut C-M-\ ("CTRL+ALT+backspace") does the
job, but since I have a danish keyboard, where "backspace" requires me
to push the META-button "Alt Gr", it seems I'm not able to push this
combination.

Any suggestions for another way to auto-indent?

Best regards,
Kenneth