I have a problem with Amazon

Change to a new address altogether.

Do you remember the address you used? If yes, you could Google it and find out what postal code goes with it.

How bout you stop lying to get better deals?

create a new account than?

Is it your account? You can chat or email with support also. I'd recommend clearing the cache and cookies from your browser. If that doesn't work, try switching browsers.

Check your emails for old orders.

You should be able to get your "billing address" (including ZIP code) from there :)

Any chance to have that zip code stored in your browser's auto complete cache?
If yes focus over there to find it.

are you tried to use some usa proxies?

Did you just randomly type in numbers or did you google for a zip code. If it's the latter then try to recreate whatever process you used. Also, 90210