How do you play when I was your man by Bruno mars on the piano the letters?

To play "When I Was Your Man" by Bruno Mars on the piano, you can use the following chord progression for the verses: C, Am, Dm, G. For the chorus, use F, G, Em, Am, Dm, and G. You can simplify it by playing the root notes or use the full chords to match the song's feel. Look up a chord chart for the specific lyrics to align the chords with the song.