@jepperi well, this is going to be tough because you don't describe exactly where you installed your roms in the first place, nor how you are using what you call a "raspberry stick". It sounds like you were trying to use USB ROM service, maybe. You need to start over and really describe your setup (see the link at the top of these pages) and explain exactly what you did (with directory paths etc.)
Also, please do some research with the Docs link above. The arcade section shows you all of the directories where emulation station is looking for roms for each emulator. The answers are right there. I shouldn't have to even write this.