HI People, I recently got hit by a car from behind. his insurance company was from geico. I called Geico to report the incident. they have accepted the claim but they are saying that they will fix the car and rent me a car in the meantime. But I just want the cheque and repair it in some other autoshop. And also, how and when do I claim regarding the compensation about the mental trauma I went through. I also missed some days of work because of the accident. I am still scared to drive. please guide and suggest me. thanks.

 I'm surprised that you actually called his insurance company. In case of an accident, the first thing you do is, jot down the culprit's insurance info and call your company (and take pics) and your insurance company will go after the guy's insurance company. 

In any case, your car needs to be assessed by some inspector (from the insurance company). You can take it to some autobody shop and take a quote, and then ask the insuanrance company to send you a check. I believe it's illegal for your insurance company to deny such request. 

Re: Mental trauma, I'm not sure if insurance will cover monetary amount for it. You could try suing the guy or his insurance company. 

 MY FREN, 
GEICO WILL GIVE YOU A ESTIMATE ABOUT YOUR DAMAGE, THEY CANT SAY THEY WILL FIX. 
YOU CAN TAKE YOUR CAR ANYWHERE TO REPAIR
FOR 2ND THING - HIRE A LAWER AND RELAX , WAIT WAIT WAIT DON PANIC :) YOU DONT NEED TO PAY TO LAWER, YES READ RIGHT "YOU DONT NEED TO PAY"  :) JUST CONTACT LAWER, HE/SHE WILL EXPLAIN ALL 
GOOD LUCK

Geico , accepted their fault, you must call your insurance and pass all the information you have gathered.

Ask your inurance to have a estimate on fixing the car, once the estimate is done , they will send you a check and you can fix your car where ever you want. You may save some from fixing out side. One of my friend got big sratch , the money he got was more than the value of the car. He kept the money , used two bottle of paint spray drove the car for another 4 years. 

If you have a liability coverage your insurance is not going to do anything. Get a lawyer if you want to sue otherwise work with geico and fix your car.