I created a kabam account like 5 years ago and only started playing again recently

Yay

I created a kabam account like 5 years ago and only returned to the game recently but I can’t remeber my account email or password from then and have no way of transferring my account to another device.

SummonerNR

If you can still get into game on older device, go to Settings then Login Options, it would tell you what email is used for that account.

But if it's been a long time since last player, then may be better just starting with a new account. Will advance much quicker than before, and would probably catch up to wherever you were in short order.