Its probably lack of light judging by the stretching. The stem wasnt strong enough to hold it so it toppled over. You are going to need real lights or put it outside
Www.growweedeasy.com I'd personally toss that plant and start over completely.(again me personally).. unless you can put that plant outdoors... but indoors that plants just going to be a waste of time imh instead of starting over properly and getting a decent yield. The plant itself looks healthy enough nutrient wise minus some burnt tips but it just doesn't have nearly the light it needs to do what it gotta do... Grow journal
The stem doesn't look very strong to withhold it. It is certainly a light issue. Try providing some artificial support to the plant and then put it in a place where there is an adequate sunlight. At night, use high-pressure sodium lights at night. (primarily used for flowering stage) and blue and white fluorescent lights at vegetative state.
