Make sure your guitar is in tune and turn it slightly. 1/16th of a turn at a time in the playing position. Give it a little time as it will not have an immediate effect, then check it.
Worst case you might need a new neck which are readily available at a few places:
http://www.vh-guitarstore.com
http://www.warmoth.com
These two places have the best prices. The first one will build anything you want very reasonable.