i have an ipad demo, and i can't reset it

Apple does not sell “demo” iPad models. If you have acquired a iPad or other Apple device with “demo” firmware installed, you should return it to the retailer for exchange or refund.

If you purchased a demo item through another channel, the iPad is very likely to have been stolen from an Apple Store or Apple Authorised Retailer. You will not be able to install “production” software on a demo device.

Demo iPads should not be sold. You should not have one of those. Return it to whoever sold it to you. It cannot normally be used.