why is it that every Nintendo 64 emulator for Android I tried don't work its just a black screen please extremely help?

Don't listen to those people, I'm playing DS games on my Android so they're full of ****. Back to the question, make sure the emulator you're using is legit, I use Super N64 emulator. Next step is finding a ROM for the game you want. Many websites offer roms but I use cool rom.com. Once you download the ROM for the game you want, select it in the emulator. If you still get a black screen the ROM may be faulty. Hope I helped

Consoles from the N64/PS1 generation forward were extremely complex, making a true pure emulator (the type that is completely legal to use) pretty much impossible. They all rely on also having a file that is a copy of the BIOS for the target system in question, and in some way pointing the emulator to it in order to function. How that is accomplished should be in the help documentation for your emulator.

It is that BIOS file that is illegal for a person to have, unless they ripped it from their own console somehow.