First, it depends what you mean by find. That could mean find a pirated copy, find a way to buy it, find the information page about it, etc.
Second, the code is not a unique identifier for a movie so having more information helps. If the code fails, usually that's because the japanese title is used to identify it instead(shouldn't be the case on this forum though unless it's very old).
For example, here's NAM-012 from prestige which is clearly different:

And here's also NAM-012 from pierrot, which is also different:
If you're looking for a downloadable copy and you can't find it on here, the place to ask is the
request section locate in the club forum section, but the chances someone has it and will post it are fairly low if it hasn't been posted somewhere before.