ag1770

when i was upgrading my firmware it was in 99% and upgrading firmware became unsuccessful when i disconnect my player to my pc it says memory error. and when i try upgrading again the firmware theres an error message and i cant continue upgrade the firmware... i cant put music in to it because sonic stage cant recognize it. and in my computer when i double click the removable disk f it says please insert a disk into drive :F so in short my computer cant recognize it anymore. pls help