Gateway NV52L Mode D'emploi page 74

change Boot Mode to UEFI. If you reinstall Windows 7, you must
change Boot Mode back to Legacy before restarting your computer.
3. The Reset your PC window opens.
4. Click Next, then choose how to erase your files:
a. Just remove my files quickly erases all files before restoring your
computer and takes about 30 minutes.
b. Fully clean the drive completely cleans the drive after each file is
erased, so no files can be viewed after the recovery. Cleaning the
drive takes much longer, up to 5 hours, but is much more secure as
old files are completely removed.
5. Click Reset.
6. The recovery process begins by restarting your computer, then
continues by copying files to your hard drive.
7. After the recovery has finished, you can start using your computer by
repeating the first-start process.
72 - Recovery
Images for reference only.