NTLDR is missing

You have to enter Windows Recovery Console :

Insert Windows Xp cd and select to boot from CD.
At Welcome to Setup press R for repair.

Select the number for your windows instalation ( most often 1 ).
Enter Administrator password. Then type :

copy x:\i386\ntldr c:\
copy x:\i386\ntdetect.com c:\

bootcfg /rebuild - to generate a new boot.ini file

Enter Load Identifier: Windows XP

Enter OS Load options: /Fastdetect  

After you boot in windows check that all 3 files are sistem, readonly and hidden so they don't get deleted again.
Open cmd, go to C:\ type attrib
To add all attributes type :
attrib +S +H +R C:\boot.ini
attrib +S +H +R C:\NTLDR
attrib +S +H +R C:\NTDETECT.COM 

If you want to manually edit boot.ini first must remove attributes :
attrib -S -H -R C:\boot.ini
then add them back :
attrib +S +H +R C:\boot.ini