On polarized receptacles the short slot is the hot side and the taller slot is neutral side. Colors can be swapped around sometimes. If they all are reversed, it is because the line is reversed somewhere, and all of the following outlets "downstream" from that one are reversed. Could even be in the main panel, if everything on the circuit is reversed.
First, ensure that the outlets are wired correctly by testing them with a multimeter to confirm the polarity. If the outlets still show reversed polarity, check for any loose connections or damaged wiring. If everything looks normal, it could be an issue with the main electrical panel or a larger wiring problem, in which case, it's best to consult a licensed electrician for further investigation and resolution.