Sorry your post got bumped to the second page because there are so many running right now.
Can you give a little more information? Like her age, if she's with others, etc? How long has she been sneezing?
First thing - regardless of your answers - is I'd get a small bottle of VetRx for your birds. It lasts forever for the little bottle. I think it's 4 ounces.
You'll want to put some diluted VetRx on a q-tip and swab her nares (nostrils) with it - use a fresh q-tip per body part.
Then use another to swab the roof of her mouth - the little cleft there. For that one, make sure the diluted VetRx is rather heavy on the q-tip as you're going to press that opening to get VetRx from the q-tip up into it. That goes into their sinuses.
Then use a little by her tear ducts. You can wash her eye out with sterile eye wash from the first aid section of the pharmacy.
There are a number of bacterial infections that can cause this, as will an injury to the eye. You can often buy terramycin opthalmic ointment at a number of feedstores. (They keep it behind the counter.) It's awesome to have around 'just in case' and lasts forever. You can wash the eye and treat it with that.
In the mean time, many of the bacterial infections that cause this sort of thing are treatable to some extent with Tylan. It's an injectable. Usually, birds that have this will be carriers if they survive. That means you will want to keep Tylan around for any time you introduce new stock to your flock, including home hatched babies. I do not usually advise using antibiotics if I think a bird is just developing an immunity to something and getting over it, especially because bacterial issues are so hard to tell from viral ones and antibiotics should always only be used if they absolutely HAVE to be. But this is one case where I might bend.
Feel free to PM me through the board if you need more help with this.