My NDS save files are GONE...

I'm so pissed~! But i dunno who or wat i should be pissed at... I lost my save files who noes how? And i didn't make any BACK UP~! So i'm really off the TOP rite now... So irritated... All my hard work is GONE... Just like dat... That is so so unfair... And it just killed my motivation to play those games again... in fact, i dun even feel like touching my NDS rite now... So very disappointed man... Arrrrgh...

Why? How?