Hi,
recently i wanted to install new windows but when trying to format that partition i couldn't so i installed it in a different partition. but i later didn't like multiple windows so i reformatted that partition by actually going through the process of installing new windows   and quiting the setup just after formatting that partition.
now when i turn on the computer , while booting three options appear first 2 for the two windows(even though now i have one)  and third for launching windows setup.how can get out of this situation, thanks!

If I read this correctly, you had a dual boot setup with two different versions of Windows.
You then removed one version by starting to install the other version on that partition.

What version of Windows do you now have on your computer [9x,2000, XP, Vista]?
If you are sure that the second version of Windows no longer exists, you can clean up the boot menu by editing it. The way to do it depends on the version of Windows you are currently using.

hi,
i am currently using windows xp pro.

   I am sure dlwolff0 was going to tell you this once you told him which Windows you had.

   That information is all in the boot.ini file in C:\.  You can edit it by opening it with Notepad.  Just remove the lines you do not want.  If it is not obvious what to remove, do a search on the internet for boot.ini and learn about it first (or you could copy it to a message here and we can tell you what to remove).
   Before you make any changes, you should save it as boot.inb or something like that so that you have a backup of it.  Then save it as boot.ini and make your changes.
   If you cannot find or open boot.ini, change the Advanced Settings on the View tab of Folder Options (get to Folder Options by right clicking on the Start button, selecting Explore from the popup menu, going to the Tools menu, and selecting Folder Options) so that system and hidden files are shown.

One problem ofter encountered when trying to edit boot.ini is that it's a read only files so the attribute has to be changed.