how do i unlock my ipad i forgot my id and passcode

For a forgotten passcode follow https://support.apple.com/en-us/HT211078

And you’ll need to figure out the Apple ID used following https://support.apple.com/en-us/HT201354

if you can’t figure it out and your iPad is in activation lock you’ll need proof of ownership, like the receipt from buying the iPhone brand new yourself and to “Start an Activation Lock support request.”  from https://al-support.apple.com/#/kbase

You won’t be able to use the iPad then. That is the purpose of iCloud activation lock, to prevent anyone other than the Apple ID owner from using a device. You would have to figure out who the owner is and ask them to remove it from their end.