I am not a crook's head
Since: Mar 14, 2003
The most popular pitch correction software is probably Antares Auto-tune. There are other brands that offer similar products, so a quick Google search would find them. They're rather expensive though. But most of them come as trial versions so you might be able to use it long enough to take care of your immediate needs.
You don't have any info in your profile about what gear you use, so we have no way of knowing what your mixing software is capable of.
But most tracking applications have an option to alter the pitch of a selected piece of a track. You'll have to zoom in on the vocal track, highlight the offending note, and look for an option in your software to alter the pitch. It'll probably be in units called cents, and you'll alter the existing note by a positive or negative number of cents to raise or lower the pitch.