Follow all the excellent advice above, but the main thing is to remember what NOT to do: i.e. strain your voice further by using it. At all, if possible. You can only cure strain by avoiding further strain, and giving the body a chance to heal itself - so complete silence is best if you can manage it. Any use at all of the vocal cords puts wear on them (and note what Anne said about whispering, which is just as bad or worse) and GIVE IT TIME! Don't go back to the choir until your voice is fully well again. Which it will be, so keep your spirits up! We've all been there -

Best of luck, Bonnie