My cedar hedge was damaged by heavy snowfall and snow blowing equipment. Many branches are bent down and partially split-apart, but still entirely green. The completely broken ones are turning brown. Can I push the split ones back together and wrap burlap twine around the split in the hope of them reattaching themselves (is there a product I should use on the split before tying them together?)

You can try splinting them, but cedars don't regenerate well. Once the cedar sap has dried up, there is no chance of them ever looking green again. Cut your losses (so to speak) and trip the brown parts out.