[doublemirchi (OP)]

Last month, I got my hands on Ubuntu Linux and tried to run it from an external USB. That backfired and now whenever I start my windows, a blue screen comes up says choose an operating system listing windows and  Ubuntu. Then it counts down 10...9...8...7...6...5...4...3... so on. How do I remove this screen. And when I open boot options in msconfig.exe, it lists only windows 8, and ubuntu completely removed from my system. Please advise. Thanks
[Windows 8 Professional 64 bit]

[RD]

NB: modifying the bootloader can make your computer unbootable , ( i.e. make it into a brick ).

Installing a Linux system has added a bootloader called GRUB.

There are tools on the Windows CD to restore your bootloader to its pre-Linux state ...

You can use the Bootrec.exe tool ...  to troubleshoot and repair the following items ...

    A master boot record (MBR)
    A boot sector
    A Boot Configuration Data (BCD) store

http://support.microsoft.com/kb/927392

The only way I can get Windows 8 to boot is to use "bootrec.exe /fixboot" and "bootrec.exe /fixmbr" from the Windows 8 cd, but this removes grub.

http://ubuntuforums.org/showthread.php?t=2067348

[syhprum]

It seldom pays to try and sort out screwed up operating systems, byte the bullet, reformat and make a fresh start !

[nicephotog]

There is a bootloader called LILO and its as common as GRUB,  there are a few others too.
Anyhow, i wouldn't say that was the best system anyhow to remove it, particularly if Ububntu does anything.
Run the Linux install rescue disc and get it to repair the boot loader it put in.
Before that, if the problem is which is "default" boot to operating system is Ubuntu and you want win, you can change that inside Ubuntu configuration apps from the start menu(usually right click on the desktop and use that graphic app that opens). You can also change the number of seconds to start booting into that the bootloader shows.
Again anyhow, like RD said , you canjust destroy the boot sector MBR by getting windows to overwrite it.

I don't know why anyone uses Ubuntu or what the hype is in the past decade, Slackware or Debian have always been excellent generic Linux flavours so i don't know why anyone gets into this type of trouble from Ubuntu.

[syhprum]

Dual boot Pro can be a great help sorting screwed up boot loaders but it takes no interest in non Windows boots.