Why can't i castle........ ARGGGGG

 i can't castle past few games i played the first one i played i clicked on my king and clicked on my rook and it worked but its not working at all any more can someone please help me

You can't castle if there is a threat on any squares your king has to move through. 

Or if you have already moved your King during the game

...or the rook of that side.

Sometimes Chess.com randomly decides that some users are not allowed to castle.  That could be happening to you. 

stars can castle kingside. crowns can castle queenside. diamonds can do both.

turds (non-subs) get the "von bardeleben" treatment ;)

What AnthonyCG said. You gotta warm your rook up before you grab it so roughly.

I'm going to save that picture :)

awesome! mr. jarkov just found an avatar! :)

Click on your king then move it to where it would be in a castled position.

Castling is a king move.

 for a while last summer I wasn't able to move any peice. i had support enter a few moves for me(thanks yall) then i found i could move by holding left while clicking right. afterwhile (a few days) it all went back to normal.... and , oh yes i am talking of a computer mouse.

thx for help im good now :)