I have 2 dell latitude E6400 if I take my hard drive and moved to other will I lose any files by chance

The time it takes for a Dell Latitude E6400 to complete a diagnostic boot can vary depending on several factors, including the specific hardware configuration of the computer, the number of diagnostic tests that are run, and the condition of the hardware.
Typically, a diagnostic boot on a Dell Latitude E6400 can take anywhere from 5 to 20 minutes, depending on the specific model and the complexity of the diagnostic tests.
The diagnostic boot process on the Dell Latitude E6400 starts with a pre-boot diagnostic test that checks the basic functionality of the computer's hardware, including the memory, hard drive, and keyboard. This test typically takes only a few minutes to complete.
After that, the system will run a more extensive set of diagnostic tests which include PSA (Pre-boot System Assessment) and ePSA (Enhanced Pre-boot System Assessment) . These tests take longer to complete and check the more in-depth hardware such as the system board, processor, and other internal components.
You can also run an extended diagnostic test that checks all the hardware components of the computer, including the memory, hard drive, and other internal components. This test takes longer to complete and is typically used when the computer is experiencing hardware-related issues.
Please note that the diagnostic boot process can take longer if the computer is experiencing hardware-related issues, and if the computer fails the diagnostic tests, it will stop the boot process and show an error message.

How to Recover Dell Latitude e6400 Bios or HDD password Feb 12 2014 USA Try this link for more details. Electro help

Seems like your hard drive is malfunctioning so in this case you might need a new replacement hard drive.

Yes this model Dell has a built-in 0.3 megapixel WEBcam. It is located at the top of the screen.

Here is a link to a video on how to do it

http://blog.parts-people.com/2011/08/31/dell-latitude-e6400-hard-drive-removal-and-installation/

Hit F12 at the Dell logo screen when you first turn on the computer. Run the diagnostic to test the hard drive. I'm 99% sure the dirve is bad.

Hello
you dont need to buy new hard drive until you confirmed that your hard drive has no more, for the purpose you need check in CMOS setup, if it is detected by computer then there is a chance to re-use the hard disk, you just need to re-install windows, during installation format the hard disk after re-partition.
if this method fails then you need to buy new one, good luck
do rate the solution if got help

have you tested the hdd? i believed dell system has quick test for ram and hdd. try this one, turn off system, press and hold on the Fn key then press once the power button while holding the Fn key. a quick test will appear to check the integrity of the hdd. if the hdd failure after the dell logo then like msgs such as no device found just try to reseat the hdd. this will not void your warranty since the hdd is a customer replaceable unit according to dell terms.