My knees make a teeth grinding sound when i climb stairs or walk after sittin or laying down. what is the reason for this?

Osteoarthritis : I wonder if you are or were involved in a lot of contact sports in your youth. Osteoarthritis or oa can cause the grinding symptoms that you are describing due to degeneration or breakdown of cartilage in the joint and loss of menisceal fluid that helps to lubricate the joints. An x-ray would be helpful to get an idea of how your joint space looks and to look for osteophytes (bony overgrowths).