Mirrored Object Not being Mirrored when i press the mirror modifer nothing happens to my shape im a noob at blender so could someone please help? i've tried all other solutions that related to my post but none of them worked.
The axis of symmetry used by the mirror modifier is the object's origin (orange dot).  

If  your object has the origin at the center of the object the mirror modifier's effect will not be visible.

Go into edit mode, displace the geometry on the desired axis to one side of the origin, and the mirror modifier's effect will be noticeable.

Pay attention also to the which axis the modifier is acting on.