After a night out drinking I woke up the next morning to find my middle finger felt sore and bruised but couldn't remember what I had done to it. The day after my finger started to swell up and within days the swelling got huge particularly behind the nail. My nail also became black and blue and it covers half or abit more of the nail. Many of my friends have told me my nail might fall off because of the pressure of the swelling will push it out however it has been about three weeks now and the swelling has gone down a lot and is 70% better and my nail is still on however it is still bruised. I was just wondering if my nail will fall off and how long it will take for a new one to grow? And if there is anything I can do to stop it!

It doesn't sound like you will lose your nail, especially if the root (bottom part) of the nail wasn't injured. The nail will continue to grow and the bruised part will eventually grow out. If there's still pain, check with your doctor.