You must reinstall Windows 7 when you are still unable to adapt to Windows 8 and are ready to uninstall. If the "Windows.old" folder that stores the original system files still exists, then we can try other methods to restore the original system as soon as possible.
First, back up all the data to make sure that the recovery is unsuccessful and data is not lost after the uninstall. Use the Windows 7 installation CD to start your computer, select the Repair computer button in the lower left corner when you go to setup, select Windows 8 in the current system listed, and select command prompt in system recovery options, using the command to use Windows 8 's windows, Program files, the Users folder is modified to a different name, and the files in the Windows.old folder where the original system files are stored are moved to the system partition root directory. Finally, go to the installation CD root and type the command "Bootbootsect/nt60 C:" (assuming the system letter is C:) to repair the startup information for Windows 7. Then restart the computer, if the original system files are not destroyed, the likelihood of successful recovery is very high.