I have a dell inspiron mini with a dell wireless

https://www.dell.com/support/article/ca/en/cabsdt1/sln302044/installing-your-wireless-sim-card-and-activating-your-mobile-broadband-service?lang=en

hello LUCA
NO OS stated, what is there XP,VISTA or windows.
did you upgrade it to w10 , that can kill any blue tooth easy.

first the PC must have that feature,
all PCs made its a feature you opt for day one new.
there are only ways to find out this.
one read the full model number of your PC and look it up
one number there on the service tag tells you what it came with new, all options.
2: or run a scanner on it like PCL-z (free and portable app)

a 3rd way is knowning where it is , one looks for it.
can be in 2 forms, separate or part if wifi module.

here are the sales sheet stated facts.
Go wherever your work takes you with Dell's superior Mobile
Broadband
2
option (available on the 14" E5400 notebook), and
Wireless-N antenna design which also supports Bluetooth® 2.1,
and is WiMAX™ ready.
Mobile Broadband 2 & GPS:
Dell Wireless 5720 (EvDo&GPS)
Mobile Broadband mini card,

Dell Wireless 5530 (Tri-band
HSDPA 7.2/HSUPA 2.0 & GPS) Mini-Card


Bluetooth
Dell Wireless 370 Bluetooth® 2.1
end quote. Marked WPAN on top.



the 370 card , must be there, seen below.

here are the ropes for bluetooth.
1: must be there, (called hardware present, and connected)
2: the driver matching the must be loaded.
3: then you turn on wifi in windows. and bluetooth goes active.
the manual for the PC tells you how to turn it on
did you lose the manual.
if you learn to google , the first hit works.
Dell E5400 manual. ever try that,? first>?
dells funky service manual skips this part totally.
like it there, names it but fails to show where it is. (found it)
ok i think it fits in the WLAN socket (3/4g)
so if that socket is empty there is no bluetooth here.



now recap, is it there.
there are 3 cards in the hatch, all are optional on most PC made.
the small card is optional model (dial up bs)
the bigger card is usually WIFI
The other car is WLAN OR WPAN,
pan means personal area network (bluetooth is one type)

if present then, make sure the drivers are not missing
did you slam Vista or w8 up to W10?
if yes, you need the dell driver

dells has them so go get them. up to windows 7
this PC is 2009 year made.

here is the driver.
http://www.dell.com/support/home/us/en/19/product-support/product/latitude-e5400/drivers


if you look there the operator book is there,
if you read it , it tells you all steps to enable bluetooth,

Step 1 Find the wireless switch, located on the front of the E5400, to the left of the touchpad.
Step 2
Slide the wireless switch into the "On" position to enable wireless radio communication on the Latitude.
Related Reading: How to Turn on Wireless on a Dell Latitude Laptop
Step 3
Click "Start ' Control Panel ' System and Maintenance ' Device Manager." Double-click "Bluetooth Adapters."
Step 4
Right-click the Bluetooth driver and then select "Enable" from the context menu, if available.
Step 5
Navigate to the Dell Support website in a Web browser if the Bluetooth Adapters category is not listed in Device Manager.
Step 6
Click "Start Here," then "Drivers Home." Click "Choose From a List of All Dell Products," then "Continue."
Step 7
Click "Laptops," "Latitude," then "Latitude E5400." Choose your operating system from the associated drop-down menu.
Step 8
Expand "Network." Click "Download File" next to the Bluetooth driver, then "Download Now."
Step 9
Launch the EXE file when the download completes. Follow the on-screen instructions to install the Bluetooth drivers to the computer.
Step 10
Restart the Latitude following setup to begin using Bluetooth on the E5400.

Right click on my computer. Click Manage. Click device manager. Right click WLAN card. Click Enable.

There is not wireless switch on this model. To turn on your wireless you will need to hold down FN + F2. If this does not turn on your wireless its most probably disabled in the Bios. To enable it, press the F2 key at the Dell Logo on startup, move down to wireless, press enter and move to wireless control, make sure its set to Fn+F2/App, then move down to wireless devices and make sure it set to on. Press Esc, and save changes and exit.

1. Ensure the wireless switch is on (Usually on the right side), slide the switch forward
2. Boot to BIOS (F2 at boot) and in the maintenance section, reset BIOS defaults
3. If Dell Control point is installed, ensure Airplane mode is OFF in Connection manager

http://support.euro.dell.com/support/downloads/index.aspx?c=ae&l=en&s=gen

follow this link and download ur latest driver

trying to fix the wifi on dell 1545 hellp

http://search.dell.com/results.aspx?c=us&l=en&s=gen&cat=sup&k=Dell+latitude+120L&rpp=12&p=1&subcat=dyd%2f1005&rf=all&nk=f&sort=K&ira=False&~srd=False&ipsys=False&advsrch=False&~ck=anav
go here
download wireless drivers
Dell Wireless 1350 WLAN MiniPCI Card, Wireless 1450 WLAN miniPCI Card, Wireless 1350 WLAN PC Card, Wireless (Except US,Japan) WLAN Card, Wi... Download this driver if you reside outside the United States and Japan. This release supports the Dell Wireless 1350, 1370, 1450,1390, 1490, and 1500 series Mini Card, MiniPCI and PC Card devices (not USB). R140745.EXE Hard-Drive 52 MB Verify Operating System and Product Compatibility