"No audio device is installed" XPS 17 (L702X)

Trouble shooting says: one or more audio services isn't running

Check to see if Windows Audio Service is running.  Go to Start/Run and type "services.msc" then hit the 'Enter' key (or click 'ok'). The Services window will appear. Scroll down until you find "Windows Audio" towards the bottom of the list. Check that it is enabled, set to automatic, and running. If it isn't, double click on it and change the Startup type to Automatic, then click Start, Apply, and OK.

If there is a problem there in services then something is wrong with Windows. Try using System Restore to undo any changes that might have caused it..

I have un installed the realtek drives and re-installed them to no avail.

You should have audio whether or not the Realtek driver is installed, because Windows can install its own driver. I would suggest that as an experiment you go ahead and install the Windows driver if nothing above has helped. To do so, remove the Realtek driver in "Remove a program". That will delete the driver files and when Windows reboots and cannot find the Realtek files it will install its own driver. If you check and find that you still have have a Realtek driver that means that more than one had been unzipped into the drivers folder on the hard drive and Windows found the 2nd one, so repeat the process until all of the Realtek drivers are removed. If there is still no audio even with the Windows driver then it's pretty certain that this is not an audio driver problem.

i pressed F12 during boot and it passed the tests and i did hear the sound but i cant get it working.

Make sure you ran the Dell Diagnostics audio tests and not just the PSA tests which only test the speakers. Both sets of tests are under F12.