1. You played on Frostmourne, not Lordaeron. There were no realm transfers from Lordaeron to Icecrown, but there were transfers from seasonal Frostmourne to Icecrown at the end of the season(s).
2. For the character(s) to be transferred to Icecrown, players had to start the process themselves. If they didn't do so within the a year from season's closure, they would be
permanently deleted.
3. For characters to be deleted there are few options. a) Character was below lvl 50 and inactive (no restoration) and was deleted due to inactivity cleanup. b) Somebody had access to account and deleted it after stealing anything valuable. Player deleted characters have restoration period of 30 days with a coin cost.
4.
https://www.warmane.com/account/barracks
5. Make sure you actually logged right account & realm. This has happened before when some return and can't find their characters.
6.
https://www.warmane.com/account/history May shed some light.
7. If the characters are indeed deleted, it may have happened long time ago (well past restoration periods if possible), meaning you'd need to start a new.