You could boot from the disc and try a repair. If you're not familiar with the repair console just select install. Once it runs the scan and finds a windows installed it will ask if you want to format the partition, repair the installation, or install to different partition. Run the repari option and it iwll auto scan and fix as needed.

It won't affect any installed programs and will leave your files alone. It's a fairly quick fix but keep in mind if you've updated to a service pack not included on the disc you'll have to reinstall that service pack again.
References :

1. Try to download " fixntldr.exe" at below link
http://tinyempire.com/notes/ntldrismissing.htm#back2research

2. Try ERD Commander 2005 ,very powerful boot disk.(highly recommend)
http://www.winternals.com/Products/AdministratorsPak/Default.aspx#erdcommander2005

Key features:

* Boots dead systems directly from CD
* Easy, familiar Windows-like interface
* Intuitive Solution Wizard helps you select the right tool to correct your system issue
* Includes Crash Analyzer Wizard to pinpoint the cause of recent system crashes for repair
* Allows complete disk sanitizing/data removal with Disk Wipe utility
* Includes the Locksmith utility to reset lost Administrator passwords
* Includes FileRestore so that you can quickly find and recover deleted files
* Provides access to XP Restore Points on unbootable Windows XP systems
* Detect malware and other applications that may be consuming system resources
* Compares key info on unbootable systems with that of a working system for diagnosis and troubleshooting
* Automatically identifies and replaces critical system files that have become corrupt
* Allows for formatting and partitioning of disks
* Provides emergency removal capability for faulty hotfixes
* Built-in network access to safely copy data to/from dead systems
* Repair and diagnostic tools located on Start menu
* Repair tools include System Restore tool, System File Repair, Service and Driver Manager, Hotfix Uninstall Wizard, Locksmith, Registry Editor, Explorer, Disk Management, and Command Prompt
* Data recovery tools include Disk Commander and FileRestore
* Diagnostic tools include Crash Analyzer Wizard, System Compare, Autoruns, Event Log Viewer, System Information, TCP/IP Configuration, and Logical volumes utilities
* Compatible with Windows NT, 2000, XP, and Server 2003

hope it helps

Ben
References :