I FIXED IT!!!
here's what i did:
1) redownloaded an OEM version of Windows 7 Pro 64bits.
2) make bootable USB with it manually using diskpart
3) boot with the USB and entered BIOS to change boot order.
4) restarted and entered command prompt from system repair.
5) entered these commands as advised by some of your members
6) Restarted and the installations went smoothly!!!
i guess the same iso that worked on one laptop might not necessarily will work on another...
THANK YOU AND A BIG HUG TO EVERYONE WHO HELPED!! <3 this forum...