If you have lost an item only a few hours ago, you should check at the Webster or Vanier Library Circulation Desk to see if it has been turned in.
If it has been more than a few hours since you lost your item, or you have already checked the Circulation Desk and your item was not there, visit the Security station on the appropriate campus to find out if your item is there (all lost and found items turned into the Circulation Desks are brought to Security daily):