I have a Galaxy S4 & I did a factory reset yesterday. Prior to that I made sure that the backup & sync function for my calendar was operating. Today when I went to add something to my calendar I noticed events on days where there shouldn't have been anything & no events on days there should! When I started looking it seems to me that my sister's partner's calendar has synced with my phone & I have none of my own calendar entries. Help. How do I get rid of all of his stuff & get mine? I tried clicking on sync but it doesn't seem to do anything...