See >>> Set up your iPhone, iPad, or iPod touch - Apple Support
re)Activation
If you are experiencing difficulties with (re)activation of your iPad, you may have more success if you connect your iPad to a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS). Once connected to your computer, your iPad will be detected - and you should be able to activate using iTunes.
- Make sure that you have the latest version of macOS or the latest version of iTunes.
- Check that your computer has an Internet connection.
- With the cable that came with your iPad, connect your iPad to your computer. Locate your device on your computer.
- Wait while your computer detects and activates your iPad:
- If you see an alert that shows "Set up as New" or "Restore from Backup", it means your iPad is activated.
- If you get an error message that says the "activation information was invalid" or "activation information could not be obtained from the device", use recovery mode to restore your iPhone.
Activation Lock
Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
Turn off Activation Lock – Apple Support
As you will discover, unless you are the owner of the AppleID that was last used to activate the device, you’ll not be able to defeat or bypass the Activation Lock. With documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple may be prepared to assist - otherwise they and nobody here will be able to help you.
If you have the necessary documentation, Apple have recently introduced a new portal though which you may be able to request release of an Activation Lock:
How to remove Activation Lock - Apple Support & start an Activation Lock support request.
AppleID
If you have forgotten your AppleID or associated password, these can be recovered here:
https://iforgot.apple.com/
To recover your credentials, you’ll need access to any one of the following:
- Your primary email address mailbox that corresponds with your AppleID
- Any of the secondary/recovery email addresses that should be configured for your AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your AppleID
Unless you AppleID account has not been fully/correctly configured, or has been seriously neglected, recovery of the AppleID and password should not be difficult.
More information about recovery of your AppleID:
If you forgot your Apple ID - Apple Support
More information about recovery of your AppleID password:
If you forgot your Apple ID password - Apple Support
When you recover access to your credentials, you would be well advised to log-in to your AppleID account from a web browser - and verify/update any email addresses and trusted telephone numbers:
https://appleid.apple.com/