A lot of times schizophrenia is genetic, but environment and changed brain structure can have a factor. So if no accident or anything happened then that means he likely showed some symptoms beforehand.
Schizophrenia is mostly chronic, though, which means that even if Randy didn't show any symptoms before his prognosis isn't good. Things like medication and therapy can greatly improve his quality of life, but if it is really schizophrenia, it'll probably either last for quite a few years or the rest of his life depending on how effective treatment is. You could make the argument that no one ever really recovers from having a mental disorder, but I'd say that overall his prognosis isn't too hot.