Why wont minecraft work when i install mods?

Answer 1

You've probably deleted something vital by accident or put the mod in the wrong place. It's always a good idea to make a few copies of your minecraft.jar if you're going to meddle with it. Need help downloading mods? There's plenty of very helpful videos on YouTube that can give you a hand. :)

If your minecraft's broken, maybe ask in the Minecraft forums for some help getting it back :)

Answer 2

If Minecraft doesn't load properly after downloading a mod, make sure you delete the META-INF folder, and that you have the correct version of forge. If you have no idea what I'm talking about, than look it up on YouTube. Oh, and for the newest Forge Universal, make sure to start minecraft before putting in the mods so that Forge can load itself.

Answer 3

Minecraft crashing can happen due to many different causes. Here's some of the most common ones.

• The Mod is not installed correctly.

  Maybe you forgot some CLASS files. Make sure to follow the instructions from the mod carefully.

• You forgot to delete META-INF.

  When installing a mod, there is a folder located in minecraft.jar. If this folder isn't deleted, you may experience errors like black-screens.

• The Mod is outdated.

  If the client and the mod does not have the same version, Minecraft will crash.

When Minecraft first crashes when booting, it usually will continue to do so. Before logging in, go to options and select "Force Update". This will give you a brand new minecraft.jar, and the crash will be fixed.

If it doesn't work, you can delete the whole .minecraft folder located in C:\Users\UserName\AppData\Roaming

Please make sure to back-up your worlds in the "saves" folder in .minecraft