If a player suffers from sudden locking of a knee while colliding with another player which ligament would be involved in that knee to cause locking?

Maybe not ligament. This might be more if a meniscal issue. A meniscus can flop over on itself if torn and cause a knee to lock up. Ligaments can cause pain and instability, but usually not locking.
Maybe meniscus. Locking is usually the result of a meniscus tear that gets stuck in the knee joint, thus the locking. See a sports medicine trained orthopedic doctor for an accurate diagnosis.