Try going to http://opengameart.org/
or similar sites to find good looking placeholder graphics and music. That should get you past the initial art slump. If you still feel unmotivated after that then you'll know what to work on next.
Also, keep in mind that making games isn't easy. It takes a lot of hard work and time, and the results aren't always what you expect. You're not the first person to be in that situation, I, and many others, have been in it as well. If it becomes too much, try taking a break from game development for a couple of days, maybe a week or two. If you keep staring at a word for too long, it'll stop looking like a word. Likewise, if you keep staring at game development for too long, it'll stop looking like a hobby and will start looking like some weird or obscure thing that will eventually drive you crazy.
I've made lots of games in my history as an indie developer, but I've not been particularly proud of any of them even though I was super motivated and excited when I started working on them. I'm not going to stop trying though, because I know that eventually success is going to get annoyed with my incessant attempts and will give in just to shut me up