My name is anand kumar i ordered a domain(.org) net4.in and paid via ccavenue (link provided by net4.in) the payment was successful and also confermed by ccavenue.

But the doamin was not delivered by net4.in in more than 26 Hours then i canceled the order and asked net4.in to return my money.

Now, It is more than a week, they are not returning my money back .

What should i do?

My account has been debited and i have confirmation mail from ccavenue.

Order number is S0429713-78497850

Sorry dude they most probably won't until you start demanding from them with some legal action.
Web4duniya also is another fraud company which cheats you with suspicious hosting plans and offers. Rest assured you will never get what you pay for. Stay away from them.

Always register you domains with world class providers such as NAME or GoDaddy.