Would you please specify what you´re actually talking about?
iOS 9.3.5 is out there since a decent while and every iPad 2 is eligible for the update. If you have updated, you are able to use the device with iOS 9.3.5.
If you have an activation lock on your device which is meant to prevent a potential thief from using it after stealing (hence the theft does not pay off therefor not worth stealing) the device, then you as the rightful owner are able to use it.
Forgot the Apple ID? Forgot sign-in credentials?