Down grade dell inspiron 5559 from windows 10 to windows 7 and i/o ports are not working

hi all

i have bought dell inpiron 5559 laptop from one week, i cleaned windows 10 pre-installed from the factory and installed windows 7 by converting hard disk style from GPT to MBR and allowing unsecure boot and changing boot sequence from UEFI to Legacy Roms

after installing windows 7, all Onboard i/o ports are not working except DVD-Drive

 for example i inserted a  USB flash memory and it wasn't recognized, i tried to install another windows and use another USB flash memory and the problem is still exist

is the operating system recovery image on dell support can solve the problem and get the laptop to its original state ? if i burned to to flash and tried to boot from it will it work and recognized or should i burn it to DVD as DVD is the only working devices right now ?