wht can i do ?..............i had inserted usb in my pc .but i cant able to eject it .pc shows the message that file has already opened ,pls close all the files otherwise you lost ur data.can any 1 me wht is d reason for this?

I used to have similiar problem. When ever i inserted my pen drive it used to show it cannot be removed or the drive is busy. I found that I have antivirus problem. I installed avira from avg so now it is not showing that problem. May that is also your problem.

pleas not chat speak/shorthand ,kiddie speak what ever its called it makes it hard to read ,

anyway from what i get out of you post it sounds like you opened a file and a windows program didn't close it ,what type of usb drive and what type of data on it .
one way i solve this for me when it happens is a go to start and log of user ,and when it logs off i log back in and try closing the usb then

there is a program called unlocker which can close, delete and move programs which windows isn't capable of closing. Hope this helps.