All of a sudden after selecting to make a new project in the first drop down box and selecting HDV, the second drop down box does not show any presets for HDV, I can only select DV Pal. So I cannot import any HDV files on to premiere pro CS6 timeline or even put any existing clips into the project panel. Any help to retreive the situation will be welcomed as I now have to revert to using CS5 on another PC.

Quick and dirty solution, assuming nothing has gone wrong with your cs6 installation, is to let Premiere do the setup for you. Make a new sequence of any sort, drop a representative clip on it and when it asks to convert the sequence to match the clip, say yes....

Not positive dropping into the timeline works with CS6. Works flawlessly in 2014 cc

Dave: Yes that trick also works in CS6.

Which window are you revering to:
The new project window or the new sequence window?
If its the second one:
Features and Sequence Presets missing | Adobe Premiere Pro CS6 (http://helpx.adobe.com/premiere-pro/kb/features-presets-missing-premiere-pro.html)

BATTLE. ANN. Thanks for the info. Will try as advised.