reverse gear won't work
Dear babe-- That sounds like bad news, but often it is not as bad as you might think. Of course you may have a transmission needing replacement (real bad), but it could be as easy as a downloaded upgrade to your TrailBlazer's computer system. I assume you are still under factory warranty (good news). Take it to a dealer. They will plug it in to their diagnostic system and should be able to give you an answer quickly. Just make sure you don't drive it into a place you have to back out of until you get it repaired. Good luck from Bovan.
Search Chevrolet TrailBlazer Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet TrailBlazer Experts