Hi! Quest do not expire over time, it’s simple in your case. You don’t play over 10 years and you just forget what have you done and what not. Besides, all quests exp/gold was changed and er-balanced. For example high lvl dungeons, if you port there low lvl wizzard he/she will not gain 100k~200k exp, just simple 500, also game balance it. To be fair for all players.
In your case, after so long time; I suggest to start new wizard character due new spells and new „beginning”. Yes now you have some nice start by Unicorn Way. Very nice and climatic, give it try.
No, quests do not expire. Quests from The Five Boxes and The Lost Pages are events that will remove their respective quests if not completed by the end of the events, but the events do come back sooner or later.
Some really early quests have been updated since so you may have received them again. I remember my max wiz received Triton Avenue's "Triton" side questline because the area got updated and revamp, which changed the location of the portal to Triton which I no longer had access to.
If it's a Mooshu or later side quest then I don't know
