As usual. There is a hidden partition on the HDD that contains the recovery data. Usually, the recovery process is described in the manual. On my Acer laptop, I have to enable "D2D recovery" in Bios, then I need to press something like Alt-F10 (forgot actually).
Also, there should be a "create recovery disc" application. Use it, and don't forget to create the "drivers and application" disc also.
i have found out how do do it again!
So all is fine now?