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Since you did not list the make or model number, this is a generic answer. Some or all of it might help you.
Windows 10 is just going to make things worse. See if the info below helps you fix 7.
That error is a catch all for many different problems. It could be that the boot sector of the hard drive is corrupted or the OS is corrupted so badly that it is not seen as a boot device. The worse case scenario is the hard drive has failed completely. Some system come with a diagnostic program in the BIOS/UEFI. If you have one, you should run it to see if it finds bad hardware.
The next thing you want to try is Advanced boot option. When you press the power button, start tapping the F8 key and the Advance boot menu should opens. Try selecting Last Known Good Configuration (your most recent settings that worked).
If that does not fix it then try running a Windows System repair disc to see if it can fix the problem. With any luck it might find a problem it can repair. If you do not have one and can find someone who has the same version of Windows you do then you can use the link below to make one.
For Windows 7 systems.
http://windows.microsoft.com/en-US/windows7/Create-a-system-repair-disc
You can skip down to the bottom part about using recovery to set it back to factory settings if there are no files you wish to recover.
If that does not work, the next thing is to try to recover your files. For this you will need a bootable thumb drive(flash drive) so you can boot the lappy. This will also allow you to verify that the lappy and its hard drive is good and all you have is a Windows problems. You will need to find a working puter to download Unetbootin USB installer. You need to read the instruction carefully and know a little about Linux to use this. There can be dragons present if you do not understand what your doing. I make no guarantees.
http://unetbootin.sourceforge.net/
Once you make the bootable thumb drive you need to add a OS for it to boot. I recommend Linux Mint ISO. Its UI is similar to Windows. Download Cinnamon 32bit.
http://linuxmint.com/
If you have a Windows 8 or above then you need to turn off secure boot and select boot from USB before using the thumb drive. The thumb drive boot will also allow you to check out the rest of the puter. If it boots and everything else works then that is a good indication that the drive is bad.
If it has a CD/DVD you can burn Linux Mint ISO right to a CD and boot with it.
Once you got the bootable thumb drive created, insert it into one of the USB ports. Also plug in the medium you selected to copy your files to. Press the power button and start tapping the F key opens the boot menu. Select the USB thumb drive and it will boot to a menu asking if you want to start Linux Mint. Click on Mint and let the system boot. Find your hard drive and copy your files to your back up medium. If the hard drive is a SATA drive it will show as sda. If it has partitions then the first partition (C Drive) will show as sda1, the next partition will show as sda2 and so on. If you have 2 drives the next drive will show as sdbx. X being the partitions if it has any. Normally external drives show as sdd or sde. I have seen Linux recover data that people claimed could not be recovered. Keep in mind while looking for your files, and this is a Vista or above version of Windows, that you have to find your USER folder. The folder will look something like this. \Users\nameofuser\Documents. Repeat that for music, pictures, and videos.
If the repair options are not working your best bet is to reset the lappy back to factory settings as if it just came out of the box. This will erase everything on the hard drive.
Post make and model and I'll post a more specific answer. Since you did not list the make and model, this is a generic answer. Some or all of it might help you.
Make sure you back up all your files before doing this.
If your resetting a lappy, make sure you have the AC adapter plugged up. You do not want this process interrupted. This should take one or two hours. It is best to check on it to make sure everything is going fine.
If your lappy came with 8 installed or above there is a good chance that fast boot is enabled. That will make it very hard to get to recovery until you turn it off.
If you can not boot into Windows then try Advanced boot option in safe mode. When you press the power button, start tapping the F8 key. If you have Windows 8 and above you have to be REALLY fast tapping the F8 key to get into safe mode. Once you get into safe mode you will see the advance boot menu. Select repair your computer. (This option is available only if the tools are installed on your computer's hard disk.) Select your language and then enter your user name and password. Then click on (brand name) factory Image Restore and next. Answer the question and it should start the recovery back to factory settings.
Recovery from the BIOS/UEFI. My preferred method.
For Acer Gateway, eMachines, press the power button and when the Acer logo appears on the screen, press the left Alt, and the F10 keys. Release them when the recovery screen opens.
For the rest you press the power button start tapping the F key for your puter and the BIOS/UEFI menu will open. Select recovery from the menu, answer the question and the recovery should begin. Depending on your puter this will take one to two hours.
Manufacturers BIOS menu F key
ASUS Del
HP/Compaq ESC
Samsung F4
Sony F2
Dell, Fijitsu, Gigabyte, Toshiba F12
Your BIOS menu should look something like this. Yours might be different. I am posting this to give you an idea of what it looks like.
ESC = BIOS menu
F1 = System Info
F2 = System Diagnostic
F9 = Boot Device options
F10 = BIOS Setup
F11 = System recovery
Anonymous
It will not upgrade properly on a corrupted system.