It sounds like you have the right mindset, but are experiencing a rough patch. It happens to everybody. Ragnola has some good advice about getting better, so I'm going to tell you a story instead.
In season 3, my goal was to hit Gold. I hadn't made it the previous season, missing out on the Victorious Jarvan skin (and Jarvan was one of my favorite champs!), so I didn't want that to happen again. I did all of my placement matches, did pretty well, and started off in Silver 1. I was fired up - just needed to climb one division! I could totally do this!
So I start up the next game... loss. Next one, loss. Next one, loss. I don't win a single game and get demoted to Silver 2. But it didn't stop there. I continued to lose, game after game, and fell into Silver 3. I hadn't won a ranked game since placements; a 10+ game losing streak. My goal was slipping away, and it was really frustrating.
So i just stopped playing ranked for a bit. I played a bunch of normals, just trying out new things, and rediscovering some old favorites. I didn't have any goals, or any focus here - I was just playing. I also started playing a lot of Coop v. AI, and just had a blast destroying the bots over and over again. Somewhere along the way, something clicked. I realized I had gotten better. I figured out how I was finding success, and on what champs.
So I went back into ranked, armed with my newfound confidence and - most importantly - my newfound experience. This time, I went on a positive run. I didn't lose a single game climbing back into Silver 1, and had over a 60% win rate with some of my champs to climb into promos for Gold. After a few attempts, I finally 3-0'd my promos, and accomplished my goal.
What I didn't realize until afterwards was that I had that major losing streak because I'd hit a wall. Some aspect of the game had gotten ahead of me, and I wasn't able to execute as well. My old strategies and mechanics weren't enough any more. By stepping back and just rediscovering the fun, and exploring stuff, I actually leveled up, and got ahead of that block.
It still happens to me every once in a while, where I get blocked and just can't seem to win. But I know now that this is a sign that I'm at a stretching point as a player - I need to overcome these growing pains, and I do that by practicing in different ways. Once I break through, not only will the wins return, but I'll KNOW that I'm a better player now that I was before.
You're probably in a growth spurt as a player right now, but you just don't know it yet. So keep your head up, and remember to have fun with it! Try a new champ, stomp some bots, watch some streams - whatever it is that works for you, find it and own it. You'll be back on your feet in no time.
GL HF!