How to get my veneers a white color?

I'm interested to know what kind of veneers you have.  It sounds like you have resin veneers, not porcelain.  I say this because it is very hard to stain porcelain veneers, because it's kind of like trying to stain your toilet bowl.  Resin on the other hand, is very easy to stain.  If your resin is stained, the only way ti fix this is to get the resin veneer redone.  If the porcelain veneers are stained, you can possibly have the stain buffed out.I hope this helps.Dr. Sarah Thompson

I would return to your dentist who can repolish your porcelain veneers using a specially made polish that is made especially for porcelain veneers. Good luck and I do hope your problem is resolved quickly. 

Hi:
If the color was changed in the process of cleaning or polishing, its best to return to your dentist to have the area repolished with porcelain polish.
Best,
Dr. Maddahi