I sympathize--got a flu two years ago and it took me three months to get the top two notes of my range again. Rest and fluids of almost any kind really are the best remedies, and besides not singing too much, rest your speaking voice as well. It affects your singing voice. And if you are really sensitive to how your voice feels when you're singing properly, be warned that it may not feel the same when you get it back, even though it will sound the same.