I have some list (where T is a custom class, and class has some properties). I would like to know how to change one or more values inside of it by using Lambda Expressions,
You could use ForEach, but you have to convert the IEnumerable to a List first.
IEnumerable
List
list.Where(w => w.Name == "height").ToList().ForEach(s => s.Value = 30);