Try the following steps.
1. uninstalled appcelerator (npm uninstall -g appcelerator).
2. Then uninstalled Node.
3. Also, delete any node directory to make sure any traces of Node was removed.
4. Reinstall Node - https://nodejs.org/en/#download
5. Reinstall appcelerator (npm install -g appcelerator)
6. Run - appc use latest -l trace
7. Run - appc setup -l trace
Hope this helps.
