It happened overnight when I was leaving for work. I'm able to shift through the gears when the car is off but it takes serious effort to get the car in first or reverse. I did put a new clutch master and slave in about 1-2 months ago. I checked the transmission fluid and it's full.

 

Check the slave cylinder for movement when the clutch pedal is depressed to the floor.

 

So it shifts fine when engine is off but difficult when it's on? BUSTED CLUTCH DISK. Likely one of the springs on the disk have come loose.