Sorry to hear you've lost something.
If you lost an item of clothing then these are kept in the Students' Union for a minimum of 2 weeks. Please come to the Students' Union Reception (above the Front Room) between 9am and 5pm.
Valuables such as keys, cards, jewellery or a phone may also be at the Reception. Items can be taken to Security at Senate house reception, so please check there as well.
If you lost something on campus then please go to University Security in Senate House. If you lost an item in the library then you could also try the information desk.