IP Help, Hacked? mirroring my IP??

Im pretty sure my ex business partner hacked into my computer, shes been in my microsoft account, deleted files, etc. and my desktop. she used to work for a company called Justice Traxx and they pretty much hacked into criminals computers for the FBI for a living. I dont know how to prove or how to find how shes gotten into my comp. Can anyone help? Is there a way to permanently change my IP address but not through a VPN or anything?