Switch for outdoor light

X-10 will do it pretty easy. You put the X-10 module in the feed to the light and a controller at the house.

Hi, Why switch? Turn the switch in "ON" position all the time and install light sensor switch in series at the post end. Another option may be wireless device(TX & RX)

If you found the break, check with the electrical inspector / code office to see if you can splice it. Something like:

X-10 MIGHT work. Line noise and the lack of error-checking means it could be very annoying.

BTW, X-10 seems to work fine on one side (power leg) of my house. On the other side, there's a lot of false operation.

What you need to do is repair your broken yard wire. THEN using the house end as the feeder, use the two existing wires as travelers , and pick up the neutral from the shop. You don't need the third wire between the switches. This is typically called a 'california three way' switch setup. It may or may not satisfy the code ninnys but it works just fine.