Operating system not found on any devices - Compaq Presario 7594 PC Desktop

There are some possibilities:
1. There is a bootable device (such as USB flash drive) attached to this laptop, but the device does not have proper operating system,
2. There is a media in the DVD drive, and it does not contain proper bootable system,
3. The hard drive is dead, so the laptop does not find any bootable device,
4. The hdd boot sector is damaged,
5. The required boot files are missing or damaged.

You can check:
- 1 & 2: check the laptop and the dvd tray,
- 3, 4 & 5: Check using DVD reinstallation media. It will check and try to install an operating system, so it will detect the previous operating system. There is an option to repair the previous operating system, so you need to read the available options. If you have valuable data in this hard drive, then you need to take out the hard drive and copy the data to the other data storage.

check boot devices, download utilities from acer, I believe you posted this twice. Check the Acer website for utilities to test your hard disk. You may need your original OS disk to boot to recovery console and use chkdsk /r to fix your corrupt OS.

it means there is no operating system on the device you are using to boot your computer. make sure you have your boot device set to your hard drive unless you are installing a new operating system if so your first boot device should be your cd/dvd and your HD peta/seta IDE second .

there is problem with your hard disk. your hard disk wire may be loose. try to remove and refix all sata wires of your hard disk. "operating system not found" message may be coming because you may have not installed any os (windows, linux or mac) in your notebook. try to install operating to system to fix this. there may also be proble with your hard disk, your hard disk may be dead. if your notebook is showing message "operating system not found" without any reason then you may have put your notebook in high magnetic field area. due to high magnetic field, sometimes hard disk's are formatted automatically.

Which Serial key are you looking for which product you not mentioned. However you have mentioned problem with operating system I am guessing that you are looking Operating system Serial key.

Operating system serial key can be found on operating system disk itself.
If you are using window XP for example then the serial key will be written over the operating disk on sticker.

if this is not the question you are asking then please mention the device for which the serial key you are looking.

When you "boot" your computer, it tries to read from all the "bootable" devices:
* diskette
* CD/DVD
* disk-drive
* USB memory-stick

for which the BIOS SETUP has listed as "bootable" devices.

If it cannot read the "boot" information from _ANY_ of those devices, it reports "operating system not found".

So, enter BIOS SETUP, and ensure that your disk-drive *IS* "detected" (i.e., not "dead")
and that it is "enabled" as one of the boot-devices.

The most-likely (and most-disasterous) cause is that your disk-drive has "died",
and the Windows operating system could not be read from the device.

Take your computer to a qualified technician, for professional trouble-shooting.
If you have the original "System Restore" set of CDs, take them, too.

For blue screen problem there is many reasons. First you check

Did you add or changed any hardware to your system recently?

Any improper shutdowns you found?

If you add any new hardware devices then remove that device and try to boot. If you found improper shutdowns then go to recovery console using your operating system disk. and use command "chkdsk" to check c drive.

On my Lenovo ThinkPad Windows 7 laptop, I have got "Operating System not found" error, to fix problem,Windows Boot Genius helped me finally!

You need to have an operatng system CD in order to put the operating system back on. If you do not have a recovery CD, then you need an OEM version of the operating system that is indicated on the operating system product key sticker usually found on the back or bottom of your computer. Or, you need a regular retail version of the operating system which will include its own product key found on a yellow sticker.

do you do any major changes do you have wincd or recovery
have you tried f1 then startup