This is presumably an external HD connected with a USB cable?... If so....
Start any time by switching on its power supply and plugging in to a USB socket.
Stop..... by pulling its USB plug or switching off! This will immediately involve you in a scolding on a pop-up window saying you can lose or corrupt your data. (Provided you were not reading or writing from it, there is little danger)
The proper way is to click on the icon on the task bar (little green arrow over a box shaped object) and choose - Stop USB storage device
hi thanks to all for the help the last time ihad to go out and needed to close down the computer the green arrow said it could not close down and to try later i was not using the ex drive at the time thanks again Chippy