I changed a 10 year old crown. The new crown looks ugly, I don't feel comfortable with it. Can a dentist make it better? (Photo)

Ms.Cintia,
The type of crown that is fixed there is a PFM crown. Usually, PFM crowns look a bit unnatural as metals ( alloy used under the white ceramic) are opaque while natural teeth are translucent( allows some amount of light to pass). 
To get excellent results ask your Dentist for metal free crowns that have translucency property similar to teeth. However, such crowns are very expensive in the US. You can discuss with your Dentist.
Hope this answer helped. Good luck.
Regards

It would be best to share your thoughts with your dentist. We have really awesome materials these days and can make a crown look just like natural tooth.  It just takes a little more effort to make it match. And it takes an artist as a technician.  Most labs hire people familiar with digital technology and not necessarily artists. A better looking crown may cost a little more so be prepared to have that discussion with your dentist as well.

The crown stands out because the tone of the color is too cold/gray. This may be due to the color of the tooth underneath the crown, due to the material used for the crown, or both. It can be made to look more natural, as long as your new dentist understands shading and materials.