The problem could be the fork or the frame itself, possibly a twist in the head tube. The fork could have one leg offset fore/aft relative to the other and/or both could be shifted sideways relative to the steerer column.

Provided the are no actual creases in the fork blades (usually on the back and just below the crown), they can be straightened. Checks and striaighterning can be done at home, but they are tedious and require removal of the forks. Most people prefer to utilize a well equipped LBS. If you're still interested in proceeding on your own, let us know.