LaunchPad totally disorganised after reboot OS X Yosemite
Go to: User directory > Library > Application Support > Dock > there, you might have a file with a strange name finishing by .db - you can do this in finder with the Go menu and paste or type the string shown below:





Put this file into the trash, but don't empty the trash, just in case.
Just restart the Mac. The Launchpad must be reinitialize, that's mean you have to remake the arrangement of all your apps, the same way at your first Lion's installation. Voilà!
If you have problems after the reboot, you can restore the file from trash to the correct location - replacing any new file that was created and then contact Apple support in that case:


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