If you are using the client, follow these steps.
If you use the browser, you will need to locate your .jar file.
If you have any mods take them out and see if it works, if it works then add the mods one by one until you find the one that's bad.
With the new launcher you should be able to select vanilla Minecraft version to see if the game works ok or not with out any add ons.
You used to be able to "force update" at the login menu to reinstall the core files but it looks like they took it away so you will have to go into the .minecraft folder (or Application Support/ minecraft folder for Mac) and save the screenshots folder and your saves folder then delete the .minecraft folder to make Minecraft redown load the core files again. Make sure you have the spare texture pack and mods to reinstall when done.
Use a mod loader to install the mods next time as it will make sure they get done right. MCPatcher and ModLoader are a couple that work.
You should re-install Minecraft, this may fix the issue.
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.
you reformat it
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?
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
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
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.