been thinking about this and im certain you have put the switched live (black and should have some red tape on )from the switch ,in with the neutrals , when you turn your circuit breaker on your lights are coming straight on till you hit the switch and make a short circuit which trips the breaker.
this could have caused your switch to weld together.
how to fix
check your switch by disconnecting it and putting a multimeter across the terminals you should get a very high ohms reading when its off and a very low reading when its on.
to find the switched live disconnect the neutrals (blacks) put the power back on check with your multimeter on volts black lead to earth red to the neutrals you shouldnt get any voltage on the correct neutrals put the switch on and one of these blacks should have 230 volts on it. turn power back off.
now this black wire is the live feed for your lights, put the rest of the reds together and the other blacks together and you should now be ok.
if you live in a brand new house yours colours will be brown (red), blue (black)
hope this helps!
but if your not sure wait for the sparky , electrickery can kill !