using System;
using System.Collections.Generic;
using System.Linq;
 
public class Test
{
	public static void Main()
	{
		List<string> list = (new string[] { 
			"Shekhar1", "Shekhar2", "Shekhar3", "Shekhar4", "Shekhar5" }
		).ToList();
 
		string match = "Shekhar3";
		string replace = "Shekhar88";
		List<string> newList = list.Select(x => x == match ? replace : x).ToList();
		list = newList;
		foreach (string value in list) {
			Console.WriteLine("{0}", value);
		}
	}
}

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