Is it permissible to use sunglasses found in an office desk drawer, and are they considered a lost item? Is it permissible to take possession of belongings left by a previous tenant in a rented apartment and move them, and what must be done to clear one's conscience?

What its owner leaves out of disinterest, there is no harm in taking possession of it, owning it, or selling it. As for what he left out of forgetfulness or intending to return for it, it belongs to its owner, and it must be returned to him if he is known. Otherwise, it is a lost item (Luqata) that must be announced for a year if it has value, after which the finder may take possession of it while guaranteeing its value to its owner should he appear. As for a trifle that its owner does not usually pursue, it is permissible to benefit from it without announcement. Items left by a previous tenant are often deliberately abandoned, unlike sunglasses, which are likely forgotten and fall under the ruling of a lost item (Luqata).