My brake warning light flashes and I noticed the brown wire going to the master cylinder switch is broken off at the switch. The brown/yellow wire is still attached to the switch. Should the two be tied together to the switch?? Or should the broken brown wire attach elsewhere??

Also, is there a way to reset the M/C switch if there is no reset button??

If the master cylinder switch has 2 tabs on it, both the wires should be connected, if can be reset by removing it and reinstalling it. If you have two tabs and the brown is disconected and your warning light is flashing check the EM brake handle
which is also connected to the warning light it may be out of adjustment or falsely
grounded

If the master cylinder switch has one tab only the brown/yellow should be connected and it should have a reset button on it. Remove this wire and
see if the light still flashed if so the trouble should be in the EM brake handle
circuit.