Cold boot of your iPad

To perform a cold reboot of your iPad, when nothing else you can do…
Press and hold the big round button, press then for 2 seconds the on-off button..

your reboot will be done..

source:  Christo Herngreen

Show – hide invisible files under OSX

Launch the Terminal and enter these commands exactly as shown. The first command activates the ability to see the hidden files:

defaults write AppleShowAllFiles TRUE

Now you must relaunch the Finder by killing it, this is how the changes take effect:
killall Finder

If you want to hide hidden files again (those preceded with a .) and go back to the default Mac settings, you can just type the following:
defaults write AppleShowAllFiles FALSE

Again you will need to kill the Finder so that it can relaunch for changes to take effect:
killall Finder

That’s all there is to it!