Knee pain, grinding sensation, locking and cracking some times gives way, if I put my hand on it I can feel it grinding worse in the cold. Any idea?

Many possibilities. Could be some arthritis (though you are young), a meniscal tear, scar tissue, or a loose body. Some people just have crackling knees without anything serious wrong with the knee. It really depends on many things...Did you have surgery before, or a major injury? It sound like you should see a sports doctor to at least have an exam and xrays.