@Awfulwaffle,
Hello. Okay, here is a possibility. At one point there may have been another light switch involved, so you may be dealing with a 3 way switch. With that said, open your box and determine, separate your wires, and determine which one(s) are hot. Remember, this box may be getting fed from more than one circuit and had been useda as a junction box. To me, what I would do is to connect the hot wire to one of the other wires and see what it powers, I suspect the box was used not only for your light, but also your receptacles. Do this for each wire. When done, you will know what wires need to be connected in order to have your receptacles working. I suspect in changing out the switch a wire end broke off or something of that nature. The switch you removed was it a 3 way?