Phone stuck on Google logo after trying to install Jelly Bean

I have a Galaxy Nexus with Android 4.0.1 I tried to install Jelly Bean, and followed all instructions I found on a website (forgot which one). I installed cwh and twh first. Then I installed Jelly Bean. After the installation I rebooted my phone and it got stuck on a cross with the four colors for more than one hour. So I tried to remove all of this (Jelly Bean, twh). But now it's stuck on Google logo. I tried everything. I don't know what to do to make my phone work. I flashed it but it's not working. Can you help me? (A stressed student who cannot pay for the repairs) Thank you , I really need an answer By the way, I have a mac.