Ever since my boss repaired the wiring for my trailer lights (i don't like electrical work) my reverse lights have not worked. The fuse was blown behind the dash. Not fixed. I tested the wiring at the lights and trailer plug and there is no power getting to them.

Am I correct to assume that the Neutral Safety / reverse light switch on the trans is probably bad?

 

No, I would assume that since they worked before your boss fixed everything you probably have a crossed wire or miswired trailer connector. Check that out first.

 

Finally had a chance to get under the truck and replace the reverse light switch on the trans and that was the cure. I guess when he was working on the trailer connection he back feed something and blew the switch, or it was a coincidence.