hi i am old player came back to this game after long time, after coming back to this game i find it that i was missing half of my old decks even the winning games on all my classes like 400/500. most importantly my decks like dino deck, jade deck, dragon deck, cursed priest deck. all of them are missing and there was no deck build as well was plane. can someone please help me? i did invest alot of time and money in this game 
Some of those changes may be due to the core card system- a rotating set of free cards that changes every year. Darkbishop benedictus, a key legend for priest, used to be in core. Now he is not. So if you used the core benedictus in a deck that deck is now incomplete. You have to use the wild version or craft it.
If you’re missing ranked class wins, that sounds like you logged in to the wrong account/region.