I just can't develop the muscle on my legs in general, I have been doing frog squats for long time but I don't see any significant progress, what other hard exercises can I do for quick mass gains on my legs.
In the end of the day, everyone is different, and will respond differently to the same exercises. Therefore, you just need to try out different things, and see what works best for you. Also, if the squats are not helping you, there might be some problems with form and technique of your squats - how certain are you that you are doing them in the right way?