If you are using the client, follow these steps.
If you use the browser, you will need to locate your .jar file.
You should re-install Minecraft, this may fix the issue.
you reformat it
to fix the everlasting loading screen on the R4 DS, get an earlier version of the software. I found a file called English-1.12 which when loaded fixes the loading problem.
TurN it on than off
It's just the way it is
If you get a black screen after installing mods, then it is a compatibility or incorrect install problem. If you get a black screen normally, force an update and this will probably fix it.
how to fix my ipod when it has frozen with the apple at the front of it all it has is a black screen with and apple t the front of it ? yes
buy another one
Have you tried deleting your addons?
The black screen means the mods you have installed are either incompatible with the game or with each other To fix this you have to force Minecraft to update minecraft.jar, which will uninstall all your mods: before you log onto Minecraft click Options, click on Force update! and click close and log in as usual
Reinstall it? And if you're using mods then navigate to .minecraft/bin and open minecraft.jar with winrar or 7zip or whichever you choose, and delete META-INF. this should fix black screen
All you have to do is delete your .minecraft folder and run Minecraft agian. It will make a new one, then try installing it agian.