That has actually happened to me, just before my GCSE Music exam. I found that I didn't have my full vocal range for about six months after a throat infection, and it was really getting me down. I found that my range came back of its own accord after that time, but I drank hot liquids (Not honey and lemon though, cos I don't like it), and resisted the temptation to sing along to my favourite songs on the radio. Every week I would try and do a bit of singing, just to see how my voice was doing, but I only sang for about five minutes at a time. I've got to admit there were times when I thought I would never be able to sing again, but about 18 months down the line from that infection, my vocal range has actually increased from 2 1/2 octaves on a good day or 1 1/2 on a bad day to 3 octaves on a good day and 2 on a bad one, so don't worry, your voice WILL come back. Honest *grin*

Love, butterflies, owls and stars,
Kat. xoxoxoxoxox