Minecraft position to find out a commandblockes?

I placed a Commandblock somewhere on the map and now I can't find it anymore, but I need it. How can I locate the command block?

There are different possibilities.

The best is probably MC Edit. There are several tools there that you should use to find the Commandblock.

You can also use X-Ray as mentioned above. Sausage or a simple texture pack is recommended.

OK