How do I set sound output to mono?

Because I live in a house with other people, I need to listen to music with headphones on. However, the left earphone unexpectedly stopped working (whilst the right still works perfectly). How do I set the output to mono so that I can properly listen to music?

EDIT: I know only the right earphone will work, but I still only hear part of the music (the part that would have normally gone only to the left earphone doesn't go to the right, even if the left is broken).

Solution 1:

I have the same situation... found a solution here

p.s. I know 2 years have passed, just not to leave the question unanswered