Force validation in ASP.Net on server side

Below code is used to apply force validation on server side.
First use anyone from below function:

Page_ClientValidate("ValidationGroupName") to validate particular group 
or 
Page_ClientValidate() to check all validator
or
Page.Validate()

Then you can just make use of this If condition

if (PageIsValid) {

  //postback only occurs when ALL validations pass.
  // You can write your further code here.

}