Once you lost your PR, it doesn't matter when you got it or how long you had it for, it's gone. Having a Canadian citizen child will not help either until he or she turns 18 and is working and can move to Canada and sponsor you. Your mother and brother may be able to sponsor you under a provincial nominee program depending on where they live, I think AB, MB and SK all have family classes in their nominee programs. Failing that, you just have to immigrate same as everybody else. Canada immigration is at
http://www.cic.gc.ca/english/immigrate/index.asp and you can read about provincial nominee programs and other immigration classes that may work for you. Good luck.