you should see who did lock the thread. This person then will have the admin privileges and would be the one you want to ask. What is the thread?
When moderators lock threads, they are supposed to put a note on the thread to indicate why they have done so, as well as it being clear which moderator did it. In this case it seems to be missing. I'm not sure who moderates that area of the forums, so I cannot really advise; whilst I could unlock the thread again, without knowing which moderator did it and their reasoning, it could only end up being locked again by them.
if you need to contact admin direct, please use the email otnfeedback_us [at] oracle.com
Just to add... looking at the thread in question (How to implement custom login page in ADF MObile Application.) I'm guessing the moderator removed your post and locked it because it's an old discussion, and perhaps your post was not justified in re-awakening the thread again.