I have tried to change which key it is bound to, it didn't work so I changed it back and it still wont work. Its not that big a deal I know but I just can't sprint no matter what I do and its annoying me.
Has anyone got any idea why it wont work?

Tried unbinding and rebinding it again? Also go into gameplay and see if controller is checked if so uncheck it....that is all I can think of for the moment. Did you use a mod or anything to change binds or just the menu?