From what i've learned from playing morrowind vampires are people who have died 3 days after being infected with Poryphic hemophillia and then rising again with a need for blood and enhanced strength but how can you be cured of death? what happens to vampires once they are cured do they regain life or are they still vampires but with all the benefits and weaknesses gone?

One idea is that people do not die, but rather go into a state of suspended animation that to any casual observer would be indistinguishable from dead. As such full blown Vamprism would be nothing more then the final stage of the disease Poryphic hemophillia. Especially if you add into that that the cure typically seems to involve drinking a potion.

Vampirism somewhat changed between Daggerfall and Oblivion, so it's not same for cure I guess.

In Daggerfall you were truly undead as far as the game says, for two weeks no less. Some might argue it was a coma but.. come on, 2 weeks with no food or drink? Nah.

In Oblivion it was a bit more like a bad cold. You just couldn't get rid of it, and it was getting worse until you get your daily dose of aspirin.

Don't forget that after getting the Cyrodiilic strain of the disease, you could not sleep at all or you'd become a vampire. The other strains took more time, but you could not pass yourself off as a normal person.

We know that the Glenmoril witches can cure both Lycanthropy and Vampirism, and we also know that Vaermina has the cure for vampirism.

It is possible to be resurrected.

From what proweler has said then maybe once you fall asleep its as if your body just does advance from there, like you have never awoken from your sleep. but then again cyrodilic vampires and vvardenfel vampires are completely diffrent, for example cyrodilic vampires can walk in the sun with minor discomfort yet have lesser strength while vvardenfel vampires cannot ever walk in the sun(from what i've seen) and have highly enhanced skills and attributes

Well, I think vampires are on the whole considered to be undead, since apparently magic effects targeted at the undead seem to work on them, and that was apparently how it was determined that Ash Vampires were infact not undead. But, it may not be necessary to have died to become undead, if being undead is simply a different form of metabolizm that your body could shift into, which would make more sense as it seems there would need to be a wizard to start you up if you actually died, but I might be thinking about necromancy too mechanically.

Maybe when you become a vampire, you die, but your soul does not leave your body. Drinking the potion somehow wakes up the soul and brings you back to life.

or you go on a quest for a crazy daedra to kill his daughter and he will turn you back to normal

that also helps