I cant record anything even when i have gone through all of the instructions. Sometimes it works and sometimes it doesnt and i cant control when it does/doesnt. 
this is really confusing How can i fix it?
I’ve no idea which version of Audacity you are using, what operating system, what sort of sound card, what you are trying to record or which instructions you are trying to follow.
The best I can do is to point you to the official documentation: http://audacityteam.org/help/documentation
and recommend that you use Audacity 1.3.12: http://audacityteam.org/download/