What happens to a MOSFET if i apply voltage between Drain and Source leaving the Gate floating?
What is likely to happen is that you create a latch. The n channel fet turns on and charges the capacitor. This activates the P channel fet. If the n channel is turned off, the cap remains charged and the P channel fet remains activated.

However, over time, the cap may slowly discharge and the P channel fet will gradually turn off. There is no other mechanism in your circuit for turning the P channel fet off. Basically, as it stands, I would describe it as a flawed circuit.