plant looks worn out and sad HELP

Just in one night my plant went from
looking nice and healthy too looking sad. the leaves have started to go down. any help would be good thanks.

http://i1285.photobucket.com/albums/a593/tonygstartony/2013-07-20134851_zpsb8309699.jpg

it looks like its over watered

Hex is right, looks like you've been drowning that thing.

Thanks guys this is my first grow and i have no exp doing this. the internet is my only help on this. i think you guys are right. it has now come back to life thanks for your help.

get rid of those pots your using, and get a paper pot. called root bag, that little girl is drowning. get it dry asap put it out side if its hot . what ever it takes, you will get root rot then your fucked

Looks like you are using a pretty heavy medium mix. This means you really need to watch your watering habits. Lift the pot now to feel how heavy it is. Then do not water again until it feels very light when lifted. When it does water until you get a little runoff from the bottom of the pot making all the medium gets water. Then just wait until the pot feels light before you water again. Follow this basic watering guideline and you will get the hang of it in no time. And next grow get some perlite to amend your medium with to aid in aeration and drainage.

Thank you you have all been very help full. I have just done a transplant to 30L pots and have used a soil could niks mix. I will let you all know how they go soon.