如何在IE＃中将IEnumerable转换为自定义类型？

I am using extension methods OrderBy and ThenBy to sort my custom collection on multiple fields. This sort does not effect the collection but instead returns and IEnumberable. I am unable to cast the IEnumerable result to my custom collection. Is there anyway to change the order of my collection or convert the IEnumerable result to my custom collection?I am using extension methods OrderBy and ThenBy