I tried downloading Cydia, and my iphone is stuck on the app?

I was downloading cydia (by Jay freeman), and i was going in and out of the app with no problem, then when i tried to go to the home screen it wouldnt let me. I can't lock my phone, or even turn it off. The screen is stuck on it but not frozen, cause i can scroll on the screen and if i hit the home button three times the options come up. Or if i hold down a link and when the options come up i press open, but it won't actually open it. I've had so many problems with this phone, but i've always managed to find some way to fix them. Its less than a year old. I also tried calling myself with another phone to try to open up a new screen but when it was about to go to voicemail a quick thing at the top pops up saying click to return to call then goes away. So the last thing i'm trying is to just leave it and hope it dies soon, but i don't know if that will even work. Is there anything else i can try and do?

Do a hard reset of your iPhone - This is done by holding down both the home and lock button of your iPhone. Don't worry, it won't erase anything, and It'll work even if the phone is completely frozen. Additionally, if you have installed a jailbreak tweak that allows you to kill processes, such as SBSettings, you can just kill the Cydia process.