iPhone or iPad users should be familiar with such service as Find my iPhone. One of the most useful features of this service is Activation Lock, which helps protect the iOS device and Apple Watch from theft and data loss, since no one else can use your device. You can enable this feature at the click of a button using your APPLE ID and password. Thus, in order to reactivate your device after a hard reset or setting up "Lost Status" in FMI, you will need to enter your Apple ID and passwords. Unfortunately, it may happen that you cannot do this, because you have forgotten your login information. First of all, try to restore it. Visit the Apple website and ask for re-login data. There is some alternative. This operation is not easy and does not work on all devices. On the GSM forums, there are a lot of advertisements about iCloud removal services. But frankly speaking, most of them are unreliable. We would not recommend you use them. Moreover, there is no guarantee of the success of the operation, so you risk losing your money.
If, when buying a used device, it turned out to be blocked, immediately ask the seller to turn off the lock. If the seller avoids this, be careful as the device may be either stolen or lost. Check this before you pay or try to return the purchase and get your money back.