A vampire will not die without blood since it’s immortal fate is sealed within its supernatural living dead body. Blood is merely needed to stay at peak power and performance as it feeds the vampire virus intertwined with their demonic DNA. It is not needed to survive. However, if a vampire denies itself blood or is somehow locked away then it will grow weaker over time until he or she enters a deep eternal sleep. In the case of being locked up, a vampire will begin to ingest its own blood which will eventually cause it to go mad! The vampire will then enter an imaginary world of their own delusional fantasies. Certainly, a blessing when one considers the immense pain they suffer without blood for long periods of time. Like a drug addict denied their precious drugs. Only a good Samaritan feeding the vampire blood will snap them out of it thereby restoring the vampire to it’s normal mental and physical state.
A vampire locked away for several months without blood would appear to be a dead person with no heartbeat or respiration what so ever. However, they are only in a perpetual delusional dream state. It’s considered the equivalent of a coma in humans. They would also have skin that looks almost grey in color with a reduction in muscle mass. After years they would start to shrivel into a desiccated mummy. There would be nothing but severely wrinkled dry grey skin covering bones! Yet a few drops of blood would begin the healing process. A complete cup would fully restore them to their former glory as if nothing had ever happened!
A vampires lust of blood is what drives it to seduce and kill humans. Although, many simply partake of people leaving them alive for another time. Despite this, a small number wish to be human again and attempt to achieve this by refusing to ingest blood. However, this has never been proved as a method to cure vampirism. They eventually give in to the bloodlust and drink again before things get too physically and mentally out of control.