Looks like you found your treat though. Sunflowers! So use them only for treats but make sure he is eating something else before you take them all away from him. It doesn't take much to starve a parrotlet.
I'm going to answer here too instead of the other post.
You need to find a way to get him out of his cage. You might try stick training see if he he feels more comfortable getting on a stick and you sloooowlllllllllly getting him out of the cage. Or do what my son started doing with his red rump and works well for the red rump. Kind of escort him out of the cage. He just kind of blocks one area out with his hand and guides Mike out of the cage....Did that make any sense?!
Or just wait for him to get out of his cage. As soon as he is take him away from the cage somewhere quiet and work with him on step up. Finger against his belly SLIGHTLY push to unbalance just a little and tell him to step up. Here's the deal with parrotlets they need their beak to step up. I don't think Peapod has ever just used her feet to step up. So it may look like he wants to bite you but he is truly only using his beak to get on your finger. Annnnnnnnnnd there will be times he really and truly is looking to bite you!
You'll learn the difference in time.
I hate to do this to you because I imagine you are quite overwhelmed at the moment. But when you can he will more than likely need a bigger cage. They need a minimum of 20 by 20 inches and the bar spacing has to be 1/2 inch of less. A lot of us go with flight cages with fit the bill on all accounts and typically cost $150.00 or less.
You know he looks really healthy and cared for actually. He certainly has toys they just need to be rotated out I usually do a biweekly rotation. They get bored need new stimulation. I wouldn't throw any of those toys out rather give them a rest and try them again see if they peak his interest down the line. I guarantee you he's not playing with most of them now because he's bored with them.
And with that said Peapod is a closet toy player. I can't catch her playing with them to save my life because we wouldn't want Ribbit (that's what Peapod calls me. I swear on a stack of bibles she has a distinct name for me. My husband noticed it) to think she does anything but mope while I am not there. All the destroyed toys on the bottom of her cage say something else.
Give him time he looks like a bright little inquisitive guy. In my experience that stance is more, WATCHA DOIN??!! HUH? HUH? Which of course means I might have to beat a hasty exit. But at least he's not all puffed up looking at you with dead eyes. Or shivering in a corner. I would bet money on this little guy. He'll give Peapod a run for her money on ornery cuteness before you know it.
I'm researching "pocket parrots" online, there is so much stuff out there! 
