If he's clipped too severely, he may now be in even more danger of hurting himself... I don't mean to guilt trip you, I only worry about his safety. Please, read through this article.
Should you clip your parrot
There are pros and cons to each side of the debate, and so many people are uneducated about both sides of the debate that they make decisions without full knowledge of why they are doing it. Worse yet, when a bird is too severely clipped by someone who doesn't know the birds body or strength and doesn't weight this into how much of the feathers should be removed.
Depending on the size of the bird and what shape they are on, only 4-10 feathers on each side need to be clipped. Here is a diagram of sorts...
The blue feathers are primary feathers and the red feathers are secondaries. The secondaries should never be clipped.
The cyan line shows a "half clip" - if cut there. This provides support for new growing feathers while still reducing flight.
The green line is the "covert clip", that is, a more severe clip than the "half clip", and may require less feathers to be clipped because you are removing more of the feather itself.
The yellow line indicates a "show clip" - which usually leaves 2-3 feathers on the end of the wing. Depending on the bird and his/her strength, this may, or may not, still allow flight. I am not a big fan of this clip.
In short, if he can't glide down, he's been clipped too far. Please offer him safe places to land by placing down some paper towels or kitchen towels that can easily be switched out for clean ones and the dirty ones washed.
Here's a good article that mentions a decent way of trimming a birds flight feathers without completely reducing flight.
Managed Flight, Not Wing Clipping
I once had a budgie that was an excellent flyer when I bought him. He didn't eat for the first 2 or 3 days that I had him, so panicked, I clipped his wings, and he started eating after that. At the time, I didn't know how to properly trim a birds flight feathers, so I gave him a too severe of a clip. This meant that he couldn't get more than 3-6 inches off the ground. When he finally did get his flights back in, he still couldn't fly. He didn't have the muscle tone required *FOR* flight. I had to "teach" him how to fly again, and I did this by tossing him onto my bed for 10-15 minuets 2-5 times per day for two weeks, thus forcing him to use his flight muscles.
After this "vigorous" training regime, he was able to fly again without assistance, but he was no longer able to fly with the grace and agility he once had.