Please need help my wireless not functioning?

i've got new laptop dell inspiron 1545 and every thing was okay, then i've installed new windows and mistakenly i've formatted all the drivers including the recovery files . since then i installed all the software needed for the new windows but i have no wireless connections when i open device manager i find yellow mark on net controller and there's no wireless icon on the tray and in the device manager says that the driver is not founded to be updated ...dont know what to do