The Music Library follows the policies as laid out by the Libraries' Facilities Department and Campus Police... see the box below for the link.
With slight variations... rather than immediately take things down to the Main Circulation Desk, where the building L&F is located, hold onto them for a few minutes - 10 to 15 at most - to see if the person comes back looking for them. If they do not then take them downstairs. Do not wait for the end of a shift - even if you are the only person working. Put the sign out and run downstairs to hand them in. Main Circulation has procedures in place to call Campus Police to collect the items.
Please note:
NEVER open a wallet.
Do not try to figure out whose phone it is
Campus Police will do that. It protects you from an accusation of theft.
The only real exception is if you know the person who left the item behind personally, and you are absolutely certain that the item belongs to them and you can text them or shoot them an IM, then feel free to do so. Do NOT open the wallet to confirm it. Don't try to unlock the phone to confirm it. If you do not know beyond a shadow of a doubt to whom it belongs, take it to L&F.
Better safe than sorry.
The Libraries' Lost and Found Policy is available here on the Internal Staff Web