I left my apartment keys to a friend of mine, and he lost them.

Legally-speaking, I think your friend should pay for the lock and key replacement since he agreed to care for them. The legal term for this is bailment. I believe that your friend (as bailee) had a duty to guard the keys reasonably (e.g. not leave them out where others could take them, etc). I don't know how your friend lost the keys, but keeping something like keys in a safe place is easy enough to do that losing them would be difficult to excuse. Is the friend accepting blame here or is he saying it is your problem? Hopefully it is the former in which case what I would do is split the lock and key replacement bill with him. If you hadn't put your keyfob with address with the keys, whoever found the keys wouldn't have known what to do with them. In other words, lost keys is no big deal. Lost keys that say what they unlock is a significantly bigger deal. By putting the keyfob with the keys, you made the loss more serious. If the friend is saying it is entirely your problem, decide for yourself is this friend is worth keeping. Hope that helps. Andy

Pay for the lock. Sue your friend in small claims if you want but, it just may ruin the friendship.

Although there may be legal concepts that apply to this scenario, this is not really a legal issue. Quite frankly, your "friend" should volunteer to pay for any out-of-pockets associated with the loss of the keys. Presumably if you don't even want to ask to be reimbursed, you're not going to sue. Try to work it out. Only you can decide what's more important; getting reimbursed or your friendship.

If you gave the keys to your friend to hold for you, and he was doing so as a favor without compensation (as is often the case between friends) then you have a "gratuitous baliment" and the standard of care for your keys is quite minimal, if at alll. You don't state how the keys were "lost" so it can't be said if you would be successful against him, as to whether he was actively negligent in caring for your keys. Having said that,, and as a practical matter, is the cost of replacing the lock worth the time, expense and effort of going to court, as well as the price of a friendship. As one other responder noted, if you hadn't placed your address info on the keys, you would not have likely faced the expense of replacement.