I can't my iPad Air 2 to restore

These support pages outline the available methods to restore an iPad - either from a backup, or to Factory Settings:

Restore your iPhone, iPad or iPod touch from a backup – Apple Support

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

Restore all content to iPad from a backup - Apple Support

If you encounter difficulties:

If you can't update or restore your iPad - Apple Support

If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

What happens when you try?

If there is an error message, what is the exact

complete text of that error message?

You need to provide more information before someone may offer a solution.

Writing an effective Apple Support Communities question:

https://discussions.apple.com/docs/DOC-5931