When a person have been entrusted with something, he is responsible for managing it whether he likes it or not. The Prophet S.A.W said:

"لا إيمان لمن لا أمانة له"

Which means: "There is no faith for the one who has no trust". (Narrated by Ahmad)

If a matter entrusted to him is lost or damaged, it is his responsibility to replace it unless the person whom has given the trust to him are willing to let the matter rest.