The second i rad the note that Harry saw in the opened locket which was the fake Horcrux, it hit me exactally what was going on. In the Order of the Phoienix, on Pg. 116.. they were going throught stuff in the Order's hideout. "Their was a heavy locket which no one could open." Their it is, that was the real horcrux! R.A.B is Regulus Black, Sirius' brother! They said he had died 16 years ago, on Voldemort's orders but did not say why he killed him. He found out Voldemort's secret and replaced the locket. Also, the women, i beleive was their sister, after sirius died and the place belonged to Harry, kept on stealing things, including the locket (horcrux).
Another theory i hold is that, Snape, if not already 'dead', i STILL beleive is a goody. It is possible that on DD's orders, snape killed him, as DD felt he was not needed any longer, and Harry would fight VMRT alone. It is also possible that Snape was really DD or that DD was really Snape via Pollyjuice. It is also possible that DD was Slughorn, who knew all about Pollyjuice. It is also possible that Snape was really a DE who was via pollyjuice. Everything, doesn't make sense, because why would Dumbledore plead for Serveus when he "trusted" him so endoudly. ("serveus...please.) There is something missing. It would be quite odd with VDMRT, Harry, Draco, and Snape in book 7, and their will no dought be a twsit, where someone he is using occlumecy, they die early, DD is alive, or something, but number 7 is going to be wicked!