I was writing a console application, I wrote a common method to reuse it like this.
"Keyword 'this' is not valid in a static property, static method, or static field initializer"
I googled and found the reason from MSDN, which says static methods are independent of any instance of the containing class - Reference
The work around i did was to create a class and place this method inside. Create a object of the class and call this method.
Hope it helps...