i bought some important stuff online and when they send it , the front desk at my building lost my package what should i do?

If you authorized delivery to be made to someone on your behalf, and they did that, then there is little you can do about it except argue with UPS or the merchandise sender and hope for the best. You may be able to stop the charge card authorization if you paid for it that way and turn it in to your credit card company as a merchant  dispute too