Are memories ever truly forgotten or are they always buried in your brain somewhere?

No, memories are not trully forgotten.

Explanation:

Even if some memories may be inaccessible for you in some moments of your life, you didn't lose them at all. You can retrieve them later. With a bit of effort, you can find the memories in your brain's unconscious part. To recover these memories, you just need a stimulus, a mental trigger (a sound, a voice, a smell or whatever), to active the emotions and feelings which will support you to find these memories.