cant install windows 7 in the preinstalled windows 8 laptop

Did the shop test the USB ports to know they are functional.

Didn't you go ahead and install via USB, or by disk?

Now that you're installed what makes you think USB doesn't work? Look in Disk Mgmt and scroll down to see if the stick is indeed recognized but doesn't have a Drive Letter. Drive Letter - Add, Change, or Remove in Windows 7 - Windows 7 Forums

gregrocker said:

Make your Recovery disks and save a System image as a secondary backup. Back up your files, unplug all other HD's and peripherals,

Boot into BIOS setup, if this is a new Win8 PC look for a setting to disable Secure Boot. Then enable Legacy BIOS or Compatibility Support Module (CSM). This should remove any EFI Boot Disk from BIOS Boot order. Set DVD drive first to boot, HDD second. Then set SATA controller to AHCI. Save changes and Exit.

Then boot into installer DVD or flash stick burned or written using tool and latest ISO for your licensed OS version here.

At first installer screen Press Shift + F10 to open a Command Box, type:

DISKPART
LIST DISK
SEL DIS 0 (after confirming Windows 7 target HD #)
CLEAN
CONVERT MBR
CREATE PARTITION PRIMARY SIZE=102400 (for 100gb partition, adjust as desired)
FORMAT FS=NTFS LABEL="WINDOWS 7"
ACTIVE
EXIT
EXIT

Next click Install Now to Clean Install Windows 7 to the partition you created. If it fails then report back at which step and the verbatim error message.

In addition read over these steps to understand the tools and methods which work best to get and maintain a perfect Clean Reinstall - Factory OEM Windows 7. The steps are the same for retail.

The purpose of creating the partition above is to wipe the HD and define an Active partition which resolves most install failures. Afterwards you can adjust the OS partition size in Disk Mgmt, create other partitions as desired.

Thanks to your outstanding knowledge i managed to write all the commands and successfully exit the installation program.After the first restart i saw that the laptop installed a gpu driver,as the resolution came out better but during the second restart the laptop enters the first installation screen(windows is loading files).This is my problem and keeps looping.I followed your commands and successfully saw that i managed to finish the installation so in the next restard i hoped to fill the name o my computer but instead of this,iam taking the first screen that says windows is loading files and again the installation procedure loops
I have an asus r556u,which had windows 10 and i am trying to downgrade to 7I changed the csm toenable ,disable the secure boot but i am in a bigproblem.I feel you are the only who can helpme.
thanks in advance

This is an old thread and is to install win 7 on a computer that came with Win 8, not 10.
- Start a new tread.
- Edit your profile with ALL your hardware specs.

New computers comes with UEFI BIOS. As I think it's your case, to install on a MBR disk can even be impossible to run. You may have to install as UEFI-GPT (Easy task)
New computers only have USB3.x ports. Win 7 installation disk doesn't have USB3.x drivers and may also require new SATA and M.2 MVMe drivers. You must add those drivers to the Win 7 installation disk.
Read my tutorial Create a Windows 7 USB flash installation with new drives for new MB's - Windows 7 Help Forums

Go to your BIOS Settings Screen, Change Boot Option from UEFI to Legacy, If you have Safe Boot Enabled just turn it Off.Change Win8 64bit to Any Other Version of Windows.