Hello Kazim. Tony and Taneese are both correct. The best thing to do before ordering ANY unlocking service (Network or iCloud), is to make a full IMEI Check. That way you will know all the information of your iPhone, and you can determine what service you will have to use and IF there is a service that can help you. Now, since your iPhone is iCloud Locked and also reported as LOST, then only the original owner can remove the iCloud Activation Screen (iCloud Lock). From our end, we can provide you all the Contact Information of the original owner, so you can reach him/her out and ask him/her to remove the iCloud Lock from your iPhone!
(Thank you Tony and Taneese for helping out Kazim!).

I need answer about an iPhone I purchased that somebody reported it lost

You cannot unlock an iCloud locked iPhone - the only fix is to get the original owner to delete it in iTunes or replace the logic board

In not sure but I would get a imei check before you pay for this service.