I seemed to have locked up the iPhone 6s plus after several attempts to unlock

I had this I phone for several years, however in updating I seemed to have locked up the phone after several attempt to unlock. I seemed to have done something after conversations with I phone it appeared I needed to send the phone in if there was any hope of retrieving my data. my daughter convinced me to go with an android. I have never been happy with this phone it is difficult for me to use (Sr. moments) I have regretted changing &loosing data, contacts etc. what I would like to do is return the old I phone & hopefully have the data retrieved & the phone usable again. I have not been happy with current phone. how might I go about returning it for repair? thank you Pat

[Edited by Moderator]