Boss Announced Change Without Telling Me, What Do I Do?

Dear experts, During a recent team meeting my manager announced publicly that I would no longer report to him/her; rather to a colleague who up until that point was a peer. I was the only team member who's reporting structure changed. This announcement came as a complete surprise to me and no further information was provided. Additionally, further requests for details and clarifications have been entirely ignored (both in person and via email). How should I interpret this change and what options are open to me? Our Twitter Advice Project (T.A.P.) is no longer an active campaign. To find an answer to the above question, please use the "Search" box in the right-hand column of this website.