My apple i book g4 is block how i unblock - Apple aluminum 13-inch MacBook laptop- Intel 2.1GHz l Core 2 Duo, 1GB 667MHz DDR2 SDRAM, 320 GB HD, ... Mac Notebook

No. You can't. Electro help

Click on this ibook g4 model a1055 Complete Manual http://manuals.info.apple.com/MANUALS/0/MA486/en_US/iBookG4GettingStarted.pdf . for more follow Apple Tech Support .

How do I block or unblock a contact? You can prevent a contact from sending you messages by adding their phone number to your Blocked list. To learn more about the effects of blocking a contact, see this article on blocking contacts in WhatsApp.
On iPhone, there are two ways to block a contact:

1. Use the Block button which is displayed when you get a message from somebody who is not in your address book:
2. Go to WhatsApp > Settings > Account > Privacy > Blocked, then tap the Add Newbutton to add contacts from your address book to your block list.

To unblock a contact, open the Blocked list with the above steps, slide your finger to the left on the contact you wish to unblock, then tap the Unblock button.
Learn how to block or unblock a contact on: Android ' BlackBerry ' Nokia S40 ' Nokia S60 'Windows Phone ' BlackBerry 10.

you'll probably need to move to a newer machine -- they're very old and even at their best are slower than any machine from the last 6 years.

Okay. Try this
http://support.apple.com/kb/TA25861?viewlocale=en_US
If it does not help then it is possible that the Back light on the screen is faulty. If you just purchased the computer, then you should go back to the vendor and ask him to change or fix it .

Yes you can do so.

you cant unblock a blocked imei due to the fact that the previous owner of your iphone decided to report the iphone as stolen and get it blocked (which i am suggesting that the phone is stolen). If you try to call whoever company then they wouldn't be able to give you any information on WHO blocked it due to data protection act. If you're the person who blocked it, you can simply call in and ask to unblock it as long as you give proof that you're the owner. Hope this helps.

Apple have software locks to stop you using the bundled disc in the "wrong" machine, get a copy of 10.4 (try eBay, ) and you should be OK

phone the apple help line (which i do believe is UK:08708760753) and give your personal details and serial number which should be on the bottom of the laptop and they should unblock it for you.