Most strains and sprains can be treated at home with an easy remedy called RICE-Rest, Ice, Compression and Elevation. Cold reduces pain and swelling and promotes healing. (Heat feels great but does more harm than good until all the swelling is gone.)
But suppose your ice tray is empty and you don't have an ice bag, what do you do? Grab a bag of frozen vegetables and wrap it in a towel or make an ice pack by wetting a towel with cold water and squeezing out the excess. Place the folded towel in a plastic bag in the freezer for 15 minutes. Voil!
Always keep a damp cloth between your skin and the ice pack. For the first 72 hours, ice for 10 minutes once an hour; after that, for 15 minutes three times a day.