If you were able to contact him via website, whois, email etc and got no reply its very likely your offer is not as tempting as you think. Without knowing name impossible to do anything but speculate.
Generally when you are ignored your offer is so far from what they want they don’t to bother answering what they might view as time wasters and frankly they don’t have to.
If you used fake name and throw away contact details that doesn’t help either. I don’t really care about fake name if the buyer is earnest but not everyone feels the same.
Did you make an offer or just inquire? Are you offering peanuts for a valuable name?
Stealth acquisition is probably better left to experienced domain brokers imo but if you are determined enough there are other ways to attempt contact. Did you try to see if the registrar holding name can let them know there is an interested party?
I mean you are probably being ignored intentionally but there are many reasons that could be. Not just what I mentioned.
Reflect on what your contact said and see if it can be improved. There are deals that take months, years and possibly longer to actually hammer out a deal acceptable to both parties.
If all else fails, there are other extensions and other names. Good Luck.