Hi there I updated my MacBook and whenever I try to boot my laptop up it displays a message saying "need to restart" etc this display on a grey screen with some writing in the left had of the screen. I have restart many times and it still doesn't go past that screen

Anyone know what to do ?

Is it a Kernel Panic? Kernel panic - Wikipedia, the free encyclopedia
If not, you could try going into safe mode (hold shift when booting up, will take a few minutes) and if that works, disable startup items (System Preferences -> Accounts -> Login ITEMS -> then delete any third party items in the list)