C# Random list that adjusts for enabled or disabled items

I am building a random roll program, I'd like it to select an item based on a number associated with it. However, I need to be able to enable or disable some of these items and adjust the roll for that new total while still maintaining a random selection. Asking for the world right?

I already have the code for the roll, and I have searched all over, but cannot find anything like an example of how to make the list so I can enable or disable items and still roll to randomly select an item from the now adjusted list.

Anyone have an idea what I'm talking about?