I (think) I accidentally screwed up my EFI or MBR installing Ubuntu

Ok. I was installing Ubuntu on my MBP. I didn't pay attention to where it was installing grub. I tried deleting ubuntu and grub. I symlinked the EFI partition, and deleted grub from there. When I boot, I get a black screen, and the sh-sh noise my mac normally makes when it boots. If it was the first time booting since I last booted successfully, it makes 1 long beep. If I shut down, wait a few minutes, and try again, I get a black screen with no beep. If I shut down, wait, boot it back up, I can boot up fine. I think I messed my up my MBR or EFI. I also did sudo fdisk -u /dev/disk0. I don't have a windows disk, and reinstalling os x is not an option, because my mom would kill me for "messing with technology." Any help would be appreciated.