Well, that's really not a lot of information to go on, as there are about 72 different kinds of 1969 $100 Federal Reserve notes. But A ballpark figure for a Choice Crisp Uncirculated example would be in the $110-$150 range.
Just as with coins, condition means everything. Paper money collectors are incredibly picky, and old folds can be spotted a mile away. You did not mention which reserve bank issued the note, but the retail "Book" value would be approximately $175. 1969 is not exactly a series that stands out in the market, but that is the retail guide. If you were selling to a dealer, (and could find one to buy it), you should expect to receive around $120 to $125. In this case, I would suggest that if you are interested in selling this piece, that you consider Ebay.
