Just go to Dell support (http://www.dell.com/support/drivers/us/en/19),
select your OS (Win 7 -- 32 or 64 bit). Don't enter your service tag as that seems to give a limited result, use your model Dell Inspiron 15 (N5030) that you can select from the list of Inspiron laptops.
First under chipset, download and install the Intel chipset driver, then do the LAN/wireless/sound/etc. You can download them all from there, just write down which driver does what as the Dell driver names are just Rxxxxxx.exe where x are various digits and it can get confusing.
And for some drivers you should use Vista drivers, as they will work fine and there are no Windows 7 specific drivers for some stuff.
I assume that you have a Windows installation disk if the entire drive was formatted, including the Dell recovery partition.