help my seedlings. someone???

i am a first timer growing in a closet...the humidity and temerature are fine as is ventilation as i have read alot on here for weeks but i cant find a post with this
my seedlings were fine lastnight they are about 2-3 inch tall with 4 decent looking but small leaves . this morning it was like small pieces of the leave have just broke off and i dont know why???
there is no discoloring either?
sorry i cant post pics

Rat? Mouse? I am un aware of any condition that causes that particular problem.

dont think its a rat but could be a mouse,i never thought of that it is possible i will see what thier like tomorrow...

OK repost then.

does anyone have any other suggestions.??????