I have a new client who has a domain name registered thru "someone"...they have no idea who. The whois shows Enom, but they say it was not registered there...so I assume it was thru a reseller.

The problem is this...he has no idea how to change the DNS info since he has no idea who to contact...and he would also like to transfer the domain to me (I resell enom also), since the domain will soon be expiring.

The contact email address on the domain is no longer valid, although his name is listed in all of the contact fields.

The domain is also locked.

How do we go about getting this transferred to me, or at least changing the DNS info?

The best thing to do is call enom.

The whois shows Enom, but they say it was not registered there...so I assume it was thru a reseller.
I am not too sure about sub-resellers, but for enom direct resellers, when you do a whois on the domain name, it should show the details of the enom reseller.
it does when you do a whois at
http://www.domainwhitepages.com/