You are a desktop support technician for your company. A user reports that her Windows 8.1 computer is missing .dll files. You need to restore the missing *dll files without losing the user's data…

System Restore is designed to revert system changes, including corrupted or missing system files like DLLs, by restoring the operating system to an earlier point in time. This process specifically preserves user's personal documents, emails, and other data files, making it suitable for resolving system file issues without data loss.

Refreshing the computer reinstalls Windows and preserves personal files, but it removes desktop apps, which is a more drastic measure than needed for missing DLLs and might require reinstalling applications.

The `wbadmin` cmdlet is used for command-line backup and recovery of entire volumes or system states, not for directly restoring individual missing DLL files.

`redmg` is not a standard Windows command for repairing missing DLL files or system restoration.