My kitty wont eat or drink & acts like shes depressed

I have had a beautiful kitty for about 3 years now that loves me to death follows me every where sleeps with me etc. We let her outside because she loves to run and jump on trees catch mice etc. but she always comes in when we call her and never stays out past 9 pm well last night she stayed out after we called her several times and we had to leave for a meeting when we came home at about 9:30 she did come when we called her but I wanted her to know that she was a bad kitty for not coming when we called her earlier and we don't like leaving her out when were not there. So my wife held her and I just tapped her on her nose and firmly told her she was a bad kitty I think she knew it before we even picked her up, anyway.
Now she wont eat or drink and wont even look at me and just hides under the bed. We took her to the vet found nothing physically wrong with her.
I don't know what to do, I want my Kitty back but, its like she isn't there anymore.
Any suggestion would be appreciated.

 

Any updates on your kitty? is she well at the moment.

 

I have a strong feeling that the kitty suffered from dehydration, My cat had the same problem before and we mixed dextrose powder to her water and she started getting her appetite back.