You have important data on your hard drive that is not backed up and your Windows installation is so corrupted you know that you must refresh the entire installation. What do you do first

Make every attempt to recover the data

Explanation:

If your decide to format the drive, use system restore or reinstall the windows OS you may end up loosing all your data so the best option is to try as much as you can attempting to recover the data because the data might or definitely will be lost while using other options you think are available.