"building database" error

I have a “sanasa express” music player.

I’ve used it for a while, but now every time i try to power it on, the screen behaves in the following manners -

  1. It writes “building database”.

  2. The bar is getting filled and empty for few times.

  3. It shows an empty battery icon and getting off. I think i’ve deleted some important system files.

how can i format the player? (i’ve tried to reset it as written in the user guide, but it’s still not working).