If you are manually installing a game backup in the NoNpDrm format, the work.bin file must be placed in a very specific directory for the Vita to recognize it: Creating Game Backups - ConsoleMods Wiki
To use a game backup, the work.bin file must be placed in a specific directory within the game's folder structure: vita work.bin
: Inside that folder, you will find a .rif file. To use it as a work.bin in a standard game folder structure: Copy the .rif file. Rename it exactly to work.bin . If you are manually installing a game backup