my ipad is frozen with black screen ..cant start

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

You must've missed this section in the link that I provided. So no you haven't already done, if you did what did Apple support say when you contacted them about your issue?

If you need more help

Contact Apple Support to set up service if you have any of these issues:

• You still see a black screen after charging, force restarting, or following the steps in this article.
• You see a black screen, but you can hear alerts, sounds, and vibrations.
• The screen remains black, but the device chirps when you unmute it and connect it to power.
• Your screen is on, but it doesn't respond when you tap, slide, or try other gestures. 
• You can't force your device to restart because a button is broken or stuck.
• Your device is stuck on the Apple logo, displays a solid color, or isn't recognized in iTunes

Please go back and follow all the steps in the link.