If you want to downgrade your Windows 8 or 8.1 into Windows 7. But you cannot continue to install Windows 7?

try cleaning the partition table through DISKUTIL, but it'll remove all the partitions that are currently created and it may make only one partition which is the primary one (usually C:) so do it on your own risk... but the data remains in the hard disk... how to recover it ?after the installation of windows7, run a recovery software (i would recommend easeus data recovery8.8 version plus the crack) to recover all the lost data and restore it.

if you old O.S is w7 and you upgrade it to w8 .8.1 or 10 and you want it to put back you old O.S w7 put to recovery it will go back to the first day you bay you loptop and O.S w7?

Simple turn off you pc plugin BOOTABLE USB or WINDOWS DVD follow the instructions select where you want to install select unallocated space click next follow the instructions