The batery in my Nokia Lumia 900 has not been keeping the charge for long periods of time andis now dead . What do I do and what caused that to happen?
Batteries have a finite lifespan. Considering the Lumia 900 is several years old at this point, I would say your battery is on its way out. You could try replacing the battery yourself if you are able to find one and possess the skills or you may be able to find a third party that can replace it for a price. Short of that, you are either going to have to deal with it or get a new phone.