condensation on the inside is usually caused by a leak in the air-con system or a blown heater matrix
if your air-con or heater aint working then that's your cause (most likely)
pollen filter is less likely, and you can tell when your pollen filter isn't working properly when outdoor odours get into the car very easily (obviously with everything closed

)
another less likely cause is damaged seals or water in the cabin...
as i said, check your heater and air-con is working properly before looking for anything else

this has happened to 2 of my mates recently and is the most common cause