Sounds to me like something happened with the transfer of the roms. (Or the roms themselves). Where did you get the roms?

Are you sure that they are the correct format/ they arent the zip files. I dont know how new you are to emulators in general.

If you downloaded a Rom from a place like coolrom there is a long process of using the downloader to save the rom then unzipping it and copyingthe actual rom out of the folder. If you haven’t done this the emulators won’t show up because the RP isnt recognizing a legitimate Rom.