12 volt circuits will have fuses NOT breakers. Breakers will all be 120VAC
Find your fuse panel. Check all fuses with an ohm meter.
Go to the first light fixture closest to the switch. Assuming the switch has power on the on side.
Take the fixture down and look. The wiring will be daisy chained and quite possibly a wife nit has come loose or a wire has pulled out killing the lights.
The bulbs should have a number on them. There are web sites that sell LED bulbs. They all have pictures and descriptions so you should be able to find them.
As for the Broken Corion, hire a professional. There is a special adhesive that they use. D9ne right the repair will nearly be invisible and last for ever. DIY you likely could wind up with a horrible looking mess.
