This is my very depressed plant! Is there anything I can do to revive it to its former glory? I have put it outside for the last week with no luck. It became very depressed after leaving it in a dark room for two days even though I was told it would be fine. And any tips on how to look after it in the future would be great
This appears to be a Fatsia japonica, and it's in such a state it's hard to be sure of anything, but I see some yellowing of leaves, it seems to be suffering serious drought (if it looked like this after two days in a dark room and before you put it outside) and it appears the pot might be too small for the plant. Keep it inside for the time being - the first thing to do is fill a bucket half full of water, put the pot into it, weight it down so it doesn't float and the pot is submerged, and let it soak thoroughly for a couple of hours. Hopefully, that will induce the foliage to stand upright again. Take it out of the water and allow to drain down freely for an hour or two, - while its doing that, check the foliage and stems thoroughly for signs of infection or infestation (fungal infections like rust or leaf spot, pest infestation such as spider mite, aphids and so on) then turn it out of its pot to see if its rootbound. If it is, pot up into something larger with good potting compost. If you're not sure what the cause of any other symptoms are, post another photo or two.Putting it outdoors without hardening off won't have helped, so if the foliage does not respond and it remains in this condition after soaking, it's likely an ex-plant...
Did you say you put this plant outside for the last couple of weeks after being an indoor plant? Plants are not meant to MOVE from environment to environment. Your plant is very stressed by being put outside. Going from a few days of total darkness to the out of doors environment would be enough stress to cause this very stressed (not depressed) plant in this picture.
Put this plant back in its old spot for another week (needs watering, do not fertilize) and hope it partially comes back. Big bummer, this guy looks fried. Plants can be stronger than we imagine however so it is worth a try. Send a picture in a week or even just a few days after a good watering and allowing this plant to go back to the environment it knows best. You might be doing some pruning soon and we can help with that. If your plant survives.
Sorry. This is how we all had to learn; the hard way.