using System;

​

public class baseclass

{

    public void changeProperties(string propertyName, object newValue)

    {            

        var prop = GetType().GetProperty(propertyName);

        if (prop == null)

            throw new NullReferenceException("Property doesn't exist!");

        else

            prop.SetValue(this, newValue);

    }

}

​

public class Test : baseclass

{

    public int Age { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var test = new Test();

        test.changeProperties("Age", 2);

        Console.WriteLine(test.Age);

    }

}