Hey i think i just screwed up my entire guard dialog in oblivion with my mod i was making and i really dont want to start over. When making my npc's dialogs i saw that it had all this dialog that i didnt give for GREETING, so i deleted all the things in greetings for guards ( because my npc had a guard class). I didnt realize until after i saved on what ive just done. Now they all say "Greetings Mortal". Is there anyway to fix it without starting over.

If I understand you correctly, you have deleted lots of vanilla greetings that you want reverted back? If so, there are several ways, but the one I like best by far, is to open your mod in TES4Edit. You will there see all changed lines, including the deleted ones, and by right-clicking on a change and selecting "Remove", you remove the change from your mod, thereby reverting it back to vanilla.