Yes, there's a place to search by confirmation number. Login, and go to My Reservations. You'll see the ones you made online. Look to the right and there's a heading that reads, Don't See All Your Reservations? Below that is a link to search by confirmation number. To do this you have to enter the reservation number and the phone number to which the reservation is linked. Unless you specify otherwise it's normally the main number that WDW has on file for you.
From there you can email the reservation to yourself so you have a print out should you wish to have one.
Good Luck!