unable to access contact list

Try a forced-restart of your iPad - as this will often clear an isolated software issue:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If the problem persists, you may need to perform a factory restore - after first ensuring that you have a current iCloud or iTunes backup of your iPad:

How to back up your iPhone, iPad, and iPod touch - Apple Support

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

At the end of the restore process, you’ll be able to restore your data from your chosen backup.