recovery partition

Some manufacturers provide recovery partitions (a hidden portion of your hard disk where a copy of the original system configuration is stored), which largely perform the same function, some do not. Recently several manufacturers have ceased to supply recovery disks and expect you to write your own from software supplied on the portable. By the time you are reading this document, this is probably not an option.

how to recore ?

read this : http://www.ucs.cam.ac.uk/support/winsupuser/recovery