According to dvla it's not been scrapped, so there is hope yet. It's been Sorned and the MOT expired in June 2013. Unfortunately the new system does not give a sorn due date as it is indefinite with that owner. Technically it's not possible to use PNC to find owner details unless an incident has occurred, but also technically it was not possible for the Titanic to sink. Perhaps someone here has a more probing system to use. Old Bike Mart has a good readership, so an ad in there might give some info. David Silver bought truck loads of 400's to restore, perhaps he has a record of yours.
Hope you are reunited eventually.
Ian