DS help

[ganonbanned]

i have both a DS and DS lite, and love both of them.  last year i got the game Kingdom hearts: chain of memories, and after a few months i was 2 levels away from winning.  i turned it on one night to play, and it said something about the Data being corrupted andall of my memory was erased.  i was pretty pissed but i figured it only took me a week to get to the end before, i could now.  i turned it off and put in a different game.  this is a game that was in my closet for a while (that had no effect there are other games that sit in there for years and have no prob playing) and my little brother recently took it out to play it.  he played for about a half hour, turned it off and watched TV.  then, he played again and got the same message! i tried played, got to the first checkpoint, turned it off and then it gave me the message.  also everytime i play this game (in my DS) it says no GBA cartridge and i have to turn it on/off 2-3 times.  at first i thought it was the DS, but then i realized that the game was screwed up.  anybody else have this problem? can i fix it? also, i bought it used.