I have a policy number but don't have insurance information or phone number

You have a real problem then... how did you get a policy without knowing who you was buying it from? THe Bills you would have paid would have had that info and address.

Oh its because a friend of mines got into a car accident and she only have the policy number

She got the number but didn't get the name of the person or what insurance company?

She could try calling the other person... (did she at least get their information?) and ask them.

Or the hard way, start calling differenct insurance companies and find out if the number is one of theirs... I'm not talking insurance brokers... but actual insurance companies.

I don't know how many actual insurance companies you have where you are... but here in the USA for example most automotive Insurance policies are issued by only about a dozen or so actual companies... but sold by tens of thousands of insurance agents/brokers. Calling the companies themselves might get results. Particularly since she should ne able to give the make and model of the car and registration number and even better the VIN.

What country is this, rules may differ. Was there a police report, who was the other driver, have you called them and asked the name of their company