Instructions
Download the free PRXUnbricker package file, from a website such as PSP Slim Hacks, onto your computer, then double-click the files to extract the file folder.
Plug a universal serial bus (USB) cable into the "USB" port on your PSP, then plug the other end of the cable into the USB port on your computer. The folder for the PSP files will appear on your computer desktop.
Scroll through the "Recovery" menu on your PSP, then select the "Toggle USB" option and press the "X" button.
Drag-and-drop the "PSP" folder in the PRXUnbricker folder to the PSP folder, then drag-and-drop the "index_0Xg.dat" to the "seplugins" folder inside the PSP folder. Unplug the PSP from the computer.
Select the "Run Program" option under the "ms0:/PSP/GAME/RECOVERY/EBOOT.PBP" directory in the Recovery menu on your PSP device.
Select the "Repair Index_0Xg.dat," then press the "X" button.