1. Download the Linux Ubuntu version 9.04 or some other version ISO image and burn it to your CD-ROM disk using programs like Power ISO...
You can also boot Linux Ubuntu version 9.04 or some other version from the USB stick.Download the Linux Ubuntu version 9.04 or some other version ISO image and also download the program called "Unetbootin".Plug in the USB stick,format it using the Windows OS options and then with the Unetbootin program select the Linux Ubuntu ISO image and your USB stick as the destination drive and put the Linux Ubuntu ISO image contents on that USB stick and thats it.You have the bootable USB stick with the Linux Ubuntu OS on it.
2. As for the NTLDR,I had this problem once.Oh man you have no idea how much i was swearing

Anyway there are 2 ways to solve this problem without losing your OS,data and settings...
--->Boot from your Windows OS CD or DVD-ROM disk and from there choose the "Recovery Console".Now in that recovery console write the following command:
copy D:\i386\NTLDR C:\ntldr
Press the ENTER button on your keyboard...
Type the following command:
copy D:\i386\NTLDR C:\WINDOWS\$NtServicePackUninstall\ntldr
Press the ENTER button on your keyboard...
NOTE: That location might not exist if your Windows OS does not have any service packs installed!!!
Type the following command:
copy D:\i386\NTLDR C:\WINDOWS\ServicePackFiles\i386\ntldr
Press the ENTER button on your keyboard...
NOTE: That location might not exist if your Windows OS does not have any service packs installed!!!
Type the following command:
copy D:\i386\NTDETECT.COM C:\NTDETECT.COM
Press the ENTER button on your keyboard...
Type the following command:
copy D:\i386\NTDETECT.COM C:\WINDOWS\ServicePackFiles\i386\ntdetect.com
Press the ENTER button on your keyboard...
NOTE: That location might not exist if your Windows OS does not have any service packs installed!!!
Now type the following command to exit from the recovery console and restart your computer:
EXIT
After your computer has restarted,you should be able to boot into your Windows OS...
NOTE 1: If you do not have the Windows OS CD or DVD-ROM disk,go on some other computer that also uses the SAME WINDOWS OS and take that "ntldr" and "NTDETECT.COM" files from there and then copy them into the SAME locations as I wrote above using the Linux Ubuntu OS!!!
NOTE 2: PAY ATTENTION ON THE LOWER CASES AND UPPER CASES for the "ntldr" file and for the "NTDETECT.COM" file.Their names on the destination locations must be the SAME as I wrote above!!!
--->If the above way did not help,you can also do the following:
Using Linux Ubuntu OS copy your entire drive "C:" on some external USB HDD.After that is finished,shutdown your computer,unplug the external USB HDD and again turn on your computer and delete ALL the partitions on your computer's HDD using the Windows OS CD or DVD-ROM disk and then format your computer's HDD using the Windows OS CD or DVD-ROM disk and then install Windows OS again.After the Windows OS is completely installed,shutdown your computer,plug in the external USB HDD again,boot into the Linux Ubuntu OS,go into that external USB HDD,select all items from there and copy them all into your computer's HDD.When you get the message wether you want to or not to replace all the existing files and folders,click MERGE ALL and on the second message click REPLACE ALL or however it is written on your Linux Ubuntu OS version...After the copying process is finished,shutdown your computer,unplug the external USB HDD from your computer and eject the Linux Ubuntu OS CD.Now turn on your computer and...viola!
IMPORTANT NOTE: When copying your entire "C:" drive on the external USB HDD using the Linux Ubuntu OS,before copying,on that external USB HDD create the folder called...let's say..."CLONE" and copy your entire "C:" drive INTO THAT FOLDER CALLED "CLONE" otherwise you will get the message which will ask do you want to replace the folder called "System Volume Information" AND THAT FOLDER MUST NOT BE REPLACED ON THAT EXTERNAL USB HDD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Cheers mate!