[header] How to format a computer [title] Backup your data. [step] When you format a computer, you will lose all of your files and data. The programs can't be backed up; they will need to be reinstalled. 
Any files-including documents, music, pictures, and videos-that you want to save need to be copied to a backup location. [substeps] You can use dvds, cds, external hard drives, flash drives, or the cloud, depending on how much data you have to backup.