Use the Missing Striped Backups window to resolve issues caused by missing data files. This window displays when a backup file you selected is one of several files created by a striped backup and you did not select all of the files required to create the virtual database.
To specify more backup files, type the path and filename of each file (or use the browse button to navigate to the target file), and then click Add.
For more information about how striped backups work, see Microsoft SQL Server Books Online.