Legal Question in Landlord & Tenant Law in Illinois

You give no zip code. Both Illinois and Chicago (as well as a few other select communities) have landlord/tenant laws and ordinances which vary somewhat. The basic rule under Illinois law is that if the landlord doesn't repair something within 14 days after written notice (which should be delivered in some manner showing actual receipt, such as certified mailing) you as the tenant can have the repair made and deduct a portion of your rent up to the statutory limit.

However, usually such mail boxes are not the property of the landlord but of the US Postal Service, which is customarily responsible for its proper usage, so your complaint may in fact be with the US Postal Service and not the landlord.

Further, neither Illinois law nor the US Postal Service provide for consequential damages such as the theft of valuable items that are improperly delivered or handled as such. However, the sender may have purchased insurance for the value of the item upon its being mailed to you (Priority Mail includes $100 with each mailing). If so with the sender can apply for insurance from the US Postal Service with the proper mailing receipt and contents paperwork and your confirmation that it was apparently stolen from the mailbox or at least never delivered to you.