Thyme tea is good for helping lost voices (but don't overdo it as it is also a diuretic). And hot lemon and honey is also good. But importantly - DON'T SING! Don't even talk if you can avoid it. You are still recovering, and you must let it happen gradually. The same thing happened to me last August - two weeks of flu, with no voice at all. A fortnight after I got better, I did a gig, and finished it with again no voice (and frightened that I'd done permanent damage). Rest and wait!