leased property

We are in a leased premises from the beginning of this year and our lease contract is signed for a period of two years. Recently, I have noticed a defect in the roofing of the building through which water is leaking. As I am occupying the premises for last four months, am I responsible for repairing such major defects? 

We have entered into a lease contract without having proper inspection on the property. The agent we appointed has confirmed that the property is in good condition. But later on, we noticed that there are many defects in the building which requires immediate maintenance. We requested the landlord for maintenance but he refused. In such a situation, can we terminate the lease contract and claim compensation from the landlord?