I am very sorry about your loss. Not all piggies cope well with being on their own. Please support feed your piggy and see whether that triggers their appetite and survival instinct again; it often does. Otherwise you are dealing with acute bereavement. Weigh daily at the same time instead of the life long once weekly.
Here is our emergency care advice if your piggy is not eating: Emergency, Crisis and Bridging Care until a Vet Appointment
Please read the two links in @Siikibam 's post. The first is about what you can do for a newly bereaved piggy (including acute bereavement) and the second contains information about how to best go about new companionship