all old IDs lost, plus emails, all paid apps are lost - can I get them back?

Three years ago I bought a generation 1 iPad. I've had to move several times since, as well as chanbe email addys and phone numbers. Most of my paperwork is gone, and I had to set up the iPad as a new machine to use it again. I had some very nice paid apps on it which are now gone. I did do a backup first, but it wants my original Apple ID and password - all gone.

Apple must have some way for me to get my paid apps back, I registered when I bought it and my identity id known.

HOW does one do this? Any help will be appreciated...