Have  CD in the  drive, make  sure  the  PC is  set  to  boot  from the
CD-ROM first .
You  may  have  to  enter  BIOS setup to  enable  this, so when the  PC
starts  tap the  DEL key [it  may  also be  the  F2 key] so look for  a
message  referring to  setup during the  boot process.
Some  proprietary  systems  EG Packard  Bell have  a  1.44MB diskette to
initiate  the  recovery  process.
Sorry  for  all the  options  here  but  you  don't  say  what  make your
system is [it  helps].

rgds
Li'l Roberto

The quick restore CDs are made by the OEM making the computer.  They are
not the same so either read the user guide or contact the computer maker
for instructions.