I slept normally through the night, woke up 7am the next day. went back to sleep 10am, until 1pm, went back to sleep 10pm until 12am. what cud b wrong?

If this is sudden : Onset and no drugs are involved, i would suspect infectious mononucleosis to be the culprit. If you have had it for a while i would get checked out physically by your family doc and then see a sleep specialist for a work up for possible narcolepsy or idiopathic central nervous system hypersomnia. If drugs are involved, treatment for that would be indicated. Best wishes.