just got it back - thank &^%$
The problem I believe was caused by a file that was x-refed into the drawing that was quite large and complex I had trouble filleting an area that crashed TC a few times (did the TC stop working and not the generate CRS file one) I was suspect but managed too fillet and saved - it seemed fine. I opened the main file this was x-refed into several times no problems and suddenly encountered a problem whilst doing what I described at the top. (filleting causes me most issues). Even while problem shootig it would not open old files of the same name even though they worked fine previous.
The extract file worked and I could recover most of the stuff so it wasn't a redraw - thks Greg.
I was looking at a re-install however re-read problems on forum, I ran TC as ADMINISTRATOR - this allowed me to open the initial problem file and delete the x-ref which had disappeared and reload a previous version from autosave, hence no need for the extract file as dwg now back to initial state.
Greg and carl for input