Hey there!
Sorry for the troubles.
Were you trying to download an app, or access some iCloud account data?
Or were you just trying to sign out, or erase the device?
I do know that if the Apple ID was deleted, and was NOT signed out of iCloud, to be more specific, if Find My was NOT disabled before doing so, you might not be able to us it anymore, as far as making any changes related to the Apple ID that require authentication, or even sign out of iCloud, erase the iPad, etc. without that Apple ID and password. I believe before deleting it, it says to sign out of all your devices, or something like that....although I miss small print all the time.
The good news is, if you do still have, or can get the receipt for the iPad, submit it to Apple, I do believe they may be able to validate you are the purchaser, and can remove the Activation Lock. (Whether the Apple ID has been deleted already, I’m not totally sure about that, but is worth a try for sure).
About Activation Lock:
https://support.apple.com/en-us/HT201365
To request support in order to request activation lock removal, as long as you have the right paperwork/original receipt, you can go here:
https://al-support.apple.com/#/getsupport
Otherwise, if you were trying something else that requires the Apple ID password, can you say?
Thanks, hope that can help!