Here is information about Activation Lock and the procedures to unlock your iPad:
https://support.apple.com/en-us/HT201365
https://support.apple.com/en-gb/HT201441
Unless you are the owner of the AppleID that was last used to activate the device, or unless you can secure the cooperation of the previous owner, you’ll not be able to defeat or bypass the Activation Lock. Without documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple won’t assist.
If you are the original owner and your device is Activation Locked, this help page will provide most of the information that you’ll need:
https://support.apple.com/en-us/HT201365
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 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:
https://support.apple.com/en-us/HT201354
More information about recovery of your AppleID password:
https://support.apple.com/en-us/HT201487
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