I woke up this morning and my phone was in the carkit mode. My last conversation was last night at 11:17 pm and this morning when I attempted to make a call at 5:22 am, no ringtone, dialtone, nothing. I could dial out, and received calls from individuals but I couldn't hear anyone and they couldn't hear me.

Snacks, think snacks. No need to have a large meal late at night.

Fault with its main board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

The orange light indicates its stuck in charging mode.
Hold volume down and power for 15 seconds, you should see the bottom buttons flash a few times and it will go into recovery mode.
Use volume keys to highlight restart phone and press power once.

try taking the battery out then put it back in. This should reset the phone.

You can't retrieve it. What you need to do is RESET it.
To reset it you need to connect it to the last computer you connected it to then.
Hold the power button and then slide to power off.
Press the power button
As soon as the apple logo appears press and hold both the top power button and the home button together until the orange triangle appears. (This should put the iPhone into restore mode)
Open itunes and restore.

Try taking the battery out and putting it back in then charging it up.

press the up volume button

I have the same phone. I have had that same problem before. What i did to fix it was to take a blowdryer (on the cool setting -not warm or hot) and take the battery out and blow the phone with it. The reason it says carkit is because moisture got into the phone somehow. Mine first started saying carkit when my friend dunked my phone in a cup of water. I hope this helps you with your phone. Also if the blowdryer doesnt work then try using a can of pressurized air.

Perform reset of device:

1. Remove the battery.
2. After 3-5 seconds, replace the battery.
3. Test phone.

If vehicle or wall charger is availalble:

1. Plug charger into the phone.
2. Power cycle the phone.
3. Attempt to place a call then remove charger while call is active.
4. Test phone.

Attempt to clean the contacts:

1. Check charging / data port for corrosion / damage.
2. Remove the battery.
3. Using a dry clean tooth brush, remove any corrosion from the charging port.
4. Replace the battery.
5. Test phone.

If device has been damaged by water, attempt to dry the phone:

1. Remove the battery.
2. Leave phone in a warm dry place for 8 - 10 hours.
3. Replace the battery.
4. Test phone.

If nothing works, take to your nearest retail store for additional troubleshooting or replacement.

I will need the model number in order to help you out with the problem