There may be a simple explanation... He may have fertilized and amended your lawn - and the weeds that were already there sprang up....

What sort of grass do you have? Have you had a soil test done to determine what's deficient?

In the short term - use a cheap, broad leaf weed killer product on the weeds... You want something that contains 2-4-D - NOT something that says it kills grass... That will knock out the majority of the "Salad fixin's"

The next thing is to start mowing regularly at the right height.....

Thanks

It's tall fescue grass

The right height would be your mower's highest setting to keep the most weeds out.

Proper watering is key to keeping weeds away. If you allow the surface of the soil to dry out completely between watering, you can stop the weeds that require daily water to germinate. Most weeds are like that. So if you are watering once a month right now in your area, that is about right. Look to go to once every 3 weeks and then every 2 weeks in April and May. In the hottest heat of summer you should be watering once a week. Note that you will have to apply water for a long time (usually) to get enough to last all month. And let Mother Nature do Her part. If She provides an inch, you won't need to water.

Moss and violets you say?

That means it's wet/damp/soggy and shady/lacks sunshine.
(how's my crystal ball working tonight?)
That's not the fault of anyone. Cut that seed guy some slack.

Install a shade garden instead.
Work with mother nature, not fight mother nature.
It's your property - your responsibly. That guy did what you asked him to do.

actually my yard gets full sun light and it's not violets it's more like the example given below

thanks for the advice everyone

Here is a link that might be useful: {{gwi:83912}}

Ok, then you have henbit and ____, what? Because moss does not grow in full sunlight.