Like the previous answer said: be sure to plot x values AND y values. MATLAB allows you to plot data in the form:
data = rand(10,1);
But this plots the data versus its index, in this case from 1 to 10. Yes, this is confusing because the plotting works, but the x-values are missing!
The plot command is normally used with x AND y values. For example, let's say the x-axis values associated with the data are from 0.1 to 1, incrementing by 0.1. Then we can plot the results as:
xdata = (0.1:0.1:1)';
ydata = rand(10,1)
You can modify the plot command, specify a figure, etc. Type "help plot" to learn more about this powerful and probably most often used MATLAB command.