You cant.
That means that you turned off your game when it was saving, and you lost your data.
sell it, buy another one. its what i done
on a ds at the back it does NT ssay ds lite and on a ds lite it says ds lite
You must get a new memory card because the one you currently have may have corrupted data.
gamestop
check the if its eu or japan
Looks like the save file is corrupt, there isn't really anything you can do to restore it, just wipe and restart.
if it says corrupted, then you cant attach it
Trytool below, it allows you to open, view, read, convert and even recover project files.
cause im cool says isata hooter
That sounds right to me. You need to downgrade your custom firmware to a lower version. Find out how to do this at http://www.wonderhowto.com/how-to-run-cso-file-2-psp/
Yes, it says so on the box.