Reinstall gem on Mac 10.5

I'm been google around try to figure out easy way to reinstall gem on my mac. I tried running the follow command.

udo gem install rails --include-dependencies sudo: gem: command not found

Please help

Thank you

I’m been google around try to figure out easy way to reinstall gem on

my mac. I tried running the follow command.

udo gem install rails --include-dependencies

sudo: gem: command not found

What gem are you trying to reinstall? Why?

-Conrad