Did you jump from version 5 to version 9? I am going to guess that you did. If the explanation below does not help, please attach a notebook that demonstrates the problem.

Since Mathematica 6, graphics have been the actual output of the plotting function. (Before 6, they were placed in the notebook as side effects.) Placing a semicolon after the plotting function prevents the output plot from appearing in the notebook.

The two workarounds are:

a) Wrap the plotting function with Print, which still uses side-effects.

Print[ Plot[Sin[x]/x, {x,-10,10}, PlotRange->All] ];  

b) Save the plots in a list or in variables and output them at the bottom of the package (no semicolon).

plts = {}; 
AppendTo[plts, ListPlot[...]]; 
AppendTo[plts, Plot3D[...] ]; 
plts 

If the problem is that you get "--Graphics--" in your notebook instead of the graphic, please see http://support.wolfram.com/kb/12490 .