The answer to your question is as follows:
You must try to find out the owner of the cover you picked up as hard as possible. It is a trust and it is your duty to give this amanah to its owner. The address on bill or scooter Number (if you remember) may help in this regard. But when you are completely failed to reach the person then hand over this responsibility to the police, they may succeed in the inquiry. You should also have a proof with you while giving it to the police for future causes if possible.
And Allah knows best
Darul Uloom Waqf Deoband
This answer was collected from the official website of Darul Uloom Deoband Waqf. The institution is based in India and the answers are provided in accordance to the Hanafi Fiqh.