The best practice against data loss is backups. You should already have a backup plan in place. If you do not, which is likely why you are reading this, and your computer will not boot you do have a few options.
If your computer has succumbed to a virus or malware, a Live rescue ISO is your best option here. They are Linux based and include scanners. You can get these from vendors like ESET, Kaspersky, etc. You should not use any other method for risk of reinfection. If your computer does not have a virus or malware present, then the remaining options are OK to use.
During a Windows Reset (local, USB or cloud), your files are automatically kept. They should be where you left them. If they are not, you can find them at
Installing Windows from a USB, select Custom Install. Select the Windows partition. Click Next. The installer will tell you your files will be moved. You can find them at
Using a separate computer, you can create a Windows-To-Go USB. Boot from this USB. Use the file manager to copy what you need. I don't recommend this because it's much slower and aimed at IT, but it is an option non-the-less. As of Windows 2004, this a depreciated.
When copying your data you should consider copying over multiple locations. Instead of just Pictures, Documents, etc. Not all software functions the same and as such data can be stored in multiple places:
C:\ProgramData houses settings pertaining to software. This location is hidden by default but can be shown with File Explorer options.
C:\Users\NAME\AppData houses two folders titled
Roaming. This location is hidden by default but can be shown with File Explorer options. Settings and data are stored here that are specific your user account. You should copy this folder. Or, you can simply copy your entire user folder.
Unfortunately, some software may save specific information to the registry. These are often tied to the current install ID that can't be recovered. Copying from the registry isn't advised. If a program stores settings there just accept your loss and start over. Merging entries could cause problems with fresh installs.
It's easy to put all your data back once you have a fresh install of Windows running.
Program settings and data is where you have to pay attention. If you did copy
ProgramData, in most cases putting the contents from these two folders back programs will pick up where you left off. But not all programs will respect this! They may ignore it and overwrite it. When putting your data back exclude folders that contain the name Microsoft or Windows, if you copied them. You just want to put data back that pertains to the programs you installed.