Is there any differences between iwanakatta and yuwanakatta (or should be better to ask: does yuwanakatta exist??):confused:

Try not to use 'yuwanakatta'. I know you hear that often in anime, but in real life, it will make you sound extremely childish in conversation. If you are over 9 or 10 years old, you simply will not be expected to say it.

Right! Thanks :)