I messed with the settings a little and now I can't select anything, trying to delete the settings file on SD card I replaced all the Mame files in the apps folder and it's own folder and i did nothing. Help.
I've done this before, where I broke FCEUX GX (dont mess with video output options, PSA)
I'd do a fresh install of MAME again to be safe, and make sure to delete any config files it has, not just /apps/MAME and /MAME/. Even though it has these directories, it's possible it's still making config files on the root of the SD.
Also try running it off of another SD/USB if you can, that way you can narrow down if it's a problem with MAME or something else.
No problem. Outta curiosity, was it a config file on the SD card root? Ive never set up mame myself, and id like to know what to do if this happens to myself (or help someone else if they stumble upon this thread)