To lock and unlock cells based on input

[social]

I am working in excel 2003.
I have a drop down box in a cell which has two options say A and B. I want certain cells to lock themselves based on input from the user, means if user selects A cells from A5 to A15 should get locked. Similarly B5 to B15 should get locked if user selects B. So I was wondering if there is some VB code or a particular function I can use to do this.
Thank you

 

[Andrew Poulsom]

Welcome to MrExcel.

You can use the Worksheet_Change event procedure:

Events In Excel VBA