If it is not working, then it is the possible that software is corrupted.
We have to restore your iPad from iTunes on your computer. Follow the steps below;
First download and install latest iTunes on your computer from here : https://www.apple.com/itunes/download/
Then connect the iPad to your computer with the USB Cable.
Open iTunes application on your computer.
iTunes will recognize your iPad. Select your iPad in the top left (select iPad icon)
Then in Summary section, click Backup and make sure "To this computer" is selected.
Then click Restore button and let it restore. It will take some time to restore the iPad.
After restoring, you will get option to restore your backup. Select Restore from backup and all your files will be restored. Let me know if you have any difficulty and I will continue to help you.
Note : You may need to go to Settings > iCloud and turn off Find My iPad to restore the iPad