Zoosk just emailed me that they were able to locate my email address with my original account after I have sent them many emails. However, I have to register with a new account. I cannot re-gain the access to my original account, which I am very disappointed although they refund me the last payment and offered me a discount to a new subscription.
It is, somehow, a relief. At least, they now finally found the fact.
I have to say that I do enjoy the company of Zoosk.