How to get Filtered Data in Crystal Report?

Your filter query doesn't look correct, you are getting all data using || condition. Suppose In your above Filter method your agent="Salman", then C# code should be

public ActionResult Index(string agent, Datetime? searchDate,string labTest, string xrayTest, string result){
//here i am assuming all data is null except agent='Salman'
// then Model code to select only data of 'salman' would be

var model= db.tbl_final_result.Include(a=>a.tbl_registration)
.Where(a=>a.tble_registration.tbl_agent.agent_name=='Salman').ToList();

return View(model);

//do not add other conditions in Where like  (agent==null || agent= "")
// it would fetch all names where name is null, or ""
//apply similarly for .Where(a=>a.Date==searchDate)
// do not add || searchDate==null || searchDate.ToString() ==""

}

Filter like above in Crystal report and you are done, thanks, upvote and mark it as answer it helped.

This is the filter query