mprep answered the question by meriting Xal0lex's post and the screenshot he posted. If the mod locks a thread, the thread startet can't unlock it. It wouldn't make much sense if he could. That would even out the decisions of mods and those made by regular users. The mod locks it, who cares, you just unlock it again. But if you contact someone from the administration team, there could be an unblocking method, like you suggested, that would allow you to reopen your thread if the staff gave their consent.