While installing my wireless driver in my dell vostro 1015 laptop i face an error " QMI module not exist? " any help?

Try downloading the driver Then you must install driver manually by going to right-click "my computer"->manage-> device manager-> other devices-> right-click on network controller -> Update driver-> No))->install from specific place->Next-> and specify the place where driver is. The Driver for xp : http://ftp.us.dell.com/network/R205204.EXE, The driver for vista: http://ftp.us.dell.com/network/R206848.exe, for win 7 it should be supported automatically.

On a dell they have either a hardware switch or a ALT-? key combination to turn the wireless on, normally it's a hw switch on the front or one of the sides with an antenna symbol. Look at the color of your ALT key and then look for the Antenna symbol or wifi symbol, Either of them should toggle the power to the wifi card.
also you can hit the windows key and look on the right side of the pop-up and find the computer link, right click on it and open properties then Device Manager, look for anything with a Yellow Triangle on it It may say Unknown Network adapter, right click on it and select properties, and then the driver tab, click update driver and explore and find the C:\Dell\drivers or c:\drivers directory and reload your wifi driver. Good Luck