My HP pavillion dv6700 laptops sound doesn't work .... the icon has a re x at the bottom and it says no audio device has been installed; it is only 2yrs. old; can this be resolved or would it be best to buy a new computer

I believe it can be resolved without purchasing a new laptop.

Windows is a 'funny animal'. Sometimes Windows just looses it. You need to reinstall your audio device Drivers again.

It's Integrated Audio used on the HP Pavilion DV6700T laptop. An audio chip soldered to the motherboard.
Another term used for Integrated Audio is OnBoard Audio.
On the motherBoard.

Chip and Chipset are slang terms for I.C.
Integrated Circuit,

http://en.wikipedia.org/wiki/Integrated_circuit

(If it wasn't Integrated Audio, it would be a separate audio adapter card. {Sound Card} The audio chip is soldered to an adapter card. The adapter card is removable. This would allow replacing the audio adapter card. Not happening for an HP Pavilion dv6700t laptop)

Drivers are small software programs that allow the Operating System to communicate with the device.
(Windows XP and Windows Vista are two examples of an Operating System. O/S)

http://en.wikipedia.org/wiki/Device_driver

There is an HP Pavilion DV6700T Entertainment Notebook PC series, and an HP Pavilion DV6700T SPECIAL EDITION Entertainment Notebook PC series of laptops.

I need to know what Operating System you are using. Do I assume Windows Vista? (Windows Vista Home Premium 32-bit)

Going with Windows Vista, here is the Audio Driver download page for the Pavilion DV6700T notebook, (Laptop),

http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?os=2093&lc=en&cc=us&dlc=en&sw_lang=&product=3650962

Doesn't matter what version of Vista it is, this audio file is for all versions of Vista.

On the above page left-click on the + sign to the left of -
Driver- Audio (1)

Now go to the right, and left-click on Download, in the rectangular box.

A small box will come up, Opening sp38899.exe
The name of this file is sp38899.exe

Left-click on Save File.

The file will be saved to, where ever your downloads are set to save to. The file needs to be found, then opened in order to work.

When you see the audio file (sp38899.exe) Double-click on it.
The Windows Installation wizard will lead you through installing.

If you are asked to restart your computer, do so.
If not, restart your computer.