How to hide and unhide Rows & Columns

Hi,

I have a worksheet that is Plan calculator for customer of a telecom company. There are four sheets,
sheet 1 Instructions (Instructions given how to put data and get result)
sheet 2 Input sheet (data to be input)
sheet 3 current Bill Data sheet (Showing cost to customer in which terrif plan he is)
sheet 4 Best bill data sheet (this sheet guaides that which plan customer should choose)
these all sheets are having so many calculations,formulas and formating. I want to know is
1) so may rows and columns are hidden and I am not able to unhide them.
2) In Input sheet al left side where row no. are there is + sing given. there are rows hide and by clicking + sign one can expande and unhide the rows I want to know to perform this task
I am attaching the excel file for your reference. I am new user and not knowing formulas and formating, help me to understand.

Thanks
Aarif