If a domain you registered on a different registrar disappeared from your account and is now registered at Sav, it most likely expired and was purchased by someone else. If that is the case, you have options for recovering it.
1. See if the domain is for sale on Sav. If you find it, buy it back.
2. If it is not for sale, contact a broker to negotiate purchasing it from its current owner.
Tip:
Avoid this problem in the future by renewing your domain.