So I don't know what to practice anymore. It seems to me that I'm stuck on a level and not really improving. I've tried to practice scales and stuff everyday for bunch of hours, and it just pisses me off that there's no improvement. Makes me wanna a kill myself. Nah I don't have any self confidence. I don't know what to do. When I sit down play, let's say, a pentatonic scale I almost start to cry because I play it in a speed that I could play already half year ago. Or it seems like I could. And downpicking. I practice downpicking and no improvement. Don't really know how to practice, and what.. I don't really want to anymore, if there's no result.
How about you take a break from just trying to improve and just play stuff that's fun to play? Then after you've goofed off a bit get back into practicing something difficult again. Also, after taking a break like that, I find that when I go back to practicing I've become a lot better, the stress release seems to help. So that's a suggestion.
There are many articles in the columns section of the site written to help you get the most you can out of your music. This is a good one that's relevant here. I reccomend taking the survey he mentions aswell, it helped me very much.
Yeah man, sounds like you just need to have some fun. I often get to feeling like you do. Then I remember why I wanted to play in the first place. (Actually it was for the chicks and free beer). Just play some songs.

The quickest way for me to start feeling inadequate is for me to just jump in and start riffing without warming up for a little while at a little slower pace. A few minutes of concentrating on doing things right and it all comes back quickly. Even the guitar greats warm up. Always practice with a metronome. It's the only way to increase your speed without being sloppy.
Jam On!