How can I use Random() with exceptions in c#? [closed]

I would like to know how can I use Random in c# with exceptions with the most effective and short way. At first , I've tried using if() but it is not effective and doesn't work for every input , so I used the if() expression in a While() loop , but i'm sure there is a much better and effective way, I would realy like to expend my knowledge , anything helps. Thank you .