machan before using a live bootable cd like ubuntu try this!
power on the computer & press & hold the key f8 continuously before log on (i.e.: at the bootable time) ! then there will be a hidden menu opening! u select safe mode in that & press enter! u'll reach to windows with minimum functions! if u can reach to windows in there just restore windows! u can bring the pc with to good condition within 3-4 minutes!
otherwise u've to use a live cd like ubuntu & take ur data & repair the os!
if u require any further information comment on me!
i'm an engineering student in moratuwa.