ahsanbhai, If your player is an 8GB player it is hacked so it may give you problems formatting it. Try using the Windows Disk Manager to format it by right clicking on My Computer, choose Manage, go to Disk Manager, right click on your player and choose format Fat. You will find once you manage to format in FAT that the true size of your chip will show.
To check the chips true size you will need to open the player and check the memory chip details against this list
HERE ,
Unfortunatly reloading firmware has lost any guarantee you may have had so your only chance of recovery is to try other firmware till you find one compatible with your player.