Old ipad and I cannot log back in

Your problem appears to be that you have forgotten your AppleID and associated password - these credentials being critical to many Apple functions and services - and in authenticating that you are the owner if faced with the Activation Lock.

Providing that your have access to your primary email account (this usually corresponds with your AppleID) - or any of your secondary/recovery email addresses that you should have configured for your AppleID account, or any of your trusted telephone numbers (either fixed landline or mobile/cellular) - then you should be able to recover your AppleID and password here:

https://iforgot.apple.com

When you have recovered access to your AppleID credentials, you can update your account here:

https://appleid.apple.com

I hope this information is helpful in resolving the problem.

Here's what you can do If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled