I have the soloution for this
worked for me on windows 7 32bit and i have dell inspiron 15 3521 core i3.open the below link
http://www.dell.com/support/drivers/us/en/19/DriverDetails/Product/inspiron-15-3521?driverId=P3DG0&osCode=W764&fileId=3183358761&languageCode=EN&categoryId=NI&dgc=SM&cid=260354&lid=4838387#
and download the one with this name
Network_Driver_P3DG0_WN_9.2.0.517_A03.EXE
just remember me in your prayers