I lost my ipad yesterday and I want to block the ipad

We are all fellow users and not Apple employees. Apple will not assist with any action involving lost or stolen property.

To disable the iPad YOU must have turned on Find My in Settings, iCloud prior to its loss. Then login to your iCloud account, go to Find My Phone, select the iPad and send a disable signal. That will disable it if it is turned on and connected to the Internet. That is the only way it can be done.

For info these are user-to-user forums, you are not talking to iTunes Support nor Apple - and Apple cannot block your iPad.

If you had Settings > iCloud > Find My iPad enabled on it then you could try locating it either via http://icloud.com on a computer or the Find My iPhone app on another iOS device - but that will only work if it's connected to a network and the device hasn't already been wiped and/or Find My iPad disabled on it (if it had iOS 7 on it as your tagline implies then it should be harder to wipe).

If you didn't have Find My iPad enabled on it then you won't be able to try and locate it.

You've reported its loss to the shopping centre and police ? As a precaution you should also change your iTunes account password, your email account passwords, and any passwords that you'd stored on websites/emails/notes etc., and if it was a cellular model then also contact the carrier.

This is a user to user forum. We cannot block or unblock your device.

To block your device you need to go icloud.com and set it to Lost mode.

iCloud: Use Lost Mode

Apple wrote:

If you can’t find your device, use Lost Mode right away to lock it with a passcode, display a custom message on the screen, and keep track of its location. Lost Mode is available with iOS 6 or later.

Only you can do this with your Apple Id and Password. Apple cannot do it for you.