First of all The question of 'free will' versus 'determinism' is one of the oldest and most complicated of philosophical problems.
It is said without free will there can be no morality, no right and wrong, no good and evil. All our behaviours would be pre-determined and we would have no creativity or choice. Free will is necessary for the notion of personal responsibility. If people do not have free will, then it is difficult to argue that they are personally and morally responsible for their actions. The problem of whether humans have free will or whether all our actions are pre-determined and our apparent free will is simply an illusion is profoundly important to humanity. It is the will that tell us whether we can determine our own future, and whether the concept of morality actually exists.
Taking for example a normal pack of playing cards consisting of 52 cards I place the Ace of Spades face down on the top of the pack. Since I am both necessarily connected to the Ace of Spades and have pre-determined knowledge of the exact card I can therefore be certain that if I turn the card from top of the pack it will be the Ace of Spades. So we see that while I have complete knowledge of the system then there is no chance or luck involved, it is all pre-determined.
Now placing these cards infront of someone who has no knowledge of the fact that the Ace of Spades is the top card. So while they are connected to the top card they do not have pre-determined knowledge, thus I ask the person to tell me which card is on top of the pack they only have one in a fifty two chance to guess it correctly. We see how chance exists when we do not have pre-determined knowledge even though we are still necessarily connected.
I think free will exists and realise that we are using chance to decide on the future of the universe, it is perhaps a balance of both free will and determinism. Thus taking for example a quote from Spinoza, both right and wrong when he writes 'There is no mind absolute or free will, but the mind is determined for willing this or that by a cause which is determined in its turn by another cause, and this one again by another, and so on to infinity.' (Spinoza, 1673) It might make sense but I cannot fully agree with it, because in the end I believe that free will is the reality, we chose what to do. Who determines what we do anyways, if you are religious is it then god?