Nokia 5800 blank sreen white

the problem is so silly which I cant find the real cause for!!! everything started after I seted up the alarm for morning then I turned off the cell.so later when I stopped the alarm it took me to a white blank screen which I cant see anything to use the cell however I removed the battery and put it back always the same think the alarm comes up I pushed stop and back to blank white screen.I tried also to remove the sim card and memory card but still have the same problem

thanks in advance