At first he was eatting his food through out the day but today he has not eaten at all? Should I take him to the vet? Or wait a few day to see if he will start eat again?

I would take him to the vet to be safe.

One day of not eating can just be put down to not feeling hungry, or feeling a bit off. 2 days of not eating and it's time for the vet.

I would give it an extra day and not free-feed.
When you leave food down the dog often picks at it through the day and doesn't feel hungry which can result in weight problems.
If you feed meals at scheduled time you will probably find the dog eats a lot better.

I feed one small meal in the morning and a larger meal at night.
An hour or so before dinner they get a walk or a run at the park. Running can really stimulate the appetite, just make sure you always wait an hour after exercising before you feed to avoid bloat.

I'm confused my the title, so has your dog not eaten for a full week or just one day?

Has there been any changes in his life or in the home, sickness or injury?

I read it as he has not been eating much for a week but the past day he hasn't eaten at all :confused: could be wrong though!

Have you changed food?