Having suffered numerous bouts of laryngitis, I cannot stress enough the importance of vocal rest. The best thing you can do is drink lots of water, sleep, and avoid talking if at all possible. Someone commented on using your normal speaking voice instead of trying to whisper. YES, it is true, whispering actually places more stress on your vocal cords than just speaking normally.
One last thing: don't expect that your voice will spring right back after a day or two of vocal rest. It usually takes a few days before you'll have some semblence of a voice again, and sometimes even weeks before you're truly back to "normal." The important thing is not to push it, or try to sing through it, or you may cause some permanent damage.
"Word of advice: Be who you are, wear what you want---just learn how to run real fast." Marc, UGLY BETTY