New at this but was progressing well in editing, tried to add title, then every thing went wrong. When opening the program it always opened with the project on the screen, now I have lost the docking window and the preview window plus the mixer, the top half of the screen is just grey or the time line fills the whole screen. I can scroll it down but nothing is above but the grey area. Tried everything but to no avail.

My first thought is to try the F11 key.
If that doesn't work, odds are that you've accidentally closed some windows.
Try re-opening them in the View menu.