I have a Macbook Pro (last version before black keyboards), and I believe I simply filled up my drive too much and now my computer won't boot up. Now that sounds silly, but it started to freeze up and I knew I had no space left. Once I turned it off, it won't boot up. The white screen with the loading screen just appears. So I tried to "T-boot" it up as an external drive on my friends mac, but nothing shows up. His Disc Utility won't find anything once I plug my computer in. Now, I could try to do a CD boot, but I have some files I'll be really sad if I lose on the computer. Is there anything else I could try? Thanks in advance.
You can boot to the disc and use disc utility without it removing anything. It will allow you to see what the problem is without necessarily taking any steps. I would boot from it, and see what it can tell you.