crystalgailswift , Use the links below to change your Sim tray/ reader. 1st link shows how to replace and the 2nd link is part available to purchase, which you can also do a search on for better pricing perhaps. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
https://www.youtube.com/watch?v=I_tZWlf6yps
https://www.amazon.ca/ePartSolution-Samsung-Galaxy-SGH-i317-Reader-Replacement/dp/B00EAXCD80