Stuck In a command block induced death loop [duplicate]

Use MCEdit to delete the command block or to break the redstone. Alternatively if you are fast enough you may be able to run a command before you die.

You can fix this without mods or external editors. A feature of the standalone Minecraft server is that it has a configuration option to disable command blocks. We can exploit this to save your game.

1. Back up your save. (Always prudent.)

2. Get and install the server somewhere on your local machine. (Follow the directions on the Minecraft Wiki if you've never done this before.)

3. Run the server once to make sure it's working, and that you can connect to it. Then stop the server.

4. Delete the contents of the server's world folder and replace it with a copy of the contents of your affected save folder.

5. Edit the server's server.properties file. Change or add the line to say:

   enable-command-block=false
   

6. Run the server and connect. Go find your errant command block and fix it or disable its clock. Wait a minute to make sure an auto-save happens, or just issue the save-all command in the server console. Stop the server again.

7. Copy the contents of the server's world file into your singleplayer saves directory. (If you want to be super-cautious, copy this into a new save folder.)

8. Play singleplayer and confirm that you don't die instantly anymore!

If it is by any chance on a server, go to your server properties folder and disable command blocks. After that, get back on your world and destroy the command block that is keeping you in the loop. Once finished, close your server and turn command blocks back on. Once you finished, it should be back to normal.

I got an way to fix it without anything like world edit.

1.Launch the Minecraft launcher and make a new profile

2.Name it

3.Set the profile's version to 1.8.9

4.You wont be able to be killed but go to the spot where the command block is. (You cant see it but I believe it seems like a black spot)

5. Blow it up with TNT

6.Go back to your other profile

7.The command block has the repeat on but it erased the command so delete the command block.

Here's an little trick for ya:

Copy this:

/Gamemode 3

Go to your world and quickly press Ctrl + V and Enter. Now, when you are right above the command block, copy this:

/Gamemode 0

Then go to settings, controls and set the "destroy block" (or something) control from button 1 (left-click) to Enter. Now press Ctrl + V and press Enter twice ASAP. Ta-da!

Having trouble with the three keys?
Use an AutoTyper program and press the type key. Now it's reduced to two keys to press in an tick. And yes, pressing three keys in a tick is possible. You might want to use some hacks if you are still having trouble with two keys. (AutoRespawn or something...) Also, if this is multiplayer, simply turn command blocks off in the menu thing.