A knocking noise in the front wheels can be a very serious problem. The knocking noise could be caused by bad ball joints. Bad ball joints can slip off the tie rods and cause the wheel assembly to collapse. This problem should be looked at as soon as possible.
Sounds like you have big problems, sounds like it has been run low on oil, and or the oil pump quit working, and you wont be driving the car much longer,it sounds like rods knocking, which means new engine time .