so I was doing a second play through of Mass effect, and since this was going to be fem shep renegade, I was dead set on romancing Garrus, but I botched the conversation that led to that romance and didn't realize this until about 7 hours of gameplay later. is there a way to reset the conversation you have with Garrus after his loyalty mission through the binary files or something of that nature so that I don't have to sink another 35 hours into ME2 to fix this.
No, unfortunately there is no way of doing that besides reloading a previous save. There are cheats that allow you to quick-save before a conversation, but there's little you can do after the conversation has occurred.
Alternatively, you may edit the 'binary files' with a save editor. However, the tables for ME2 doesn't seem to be as clear as for ME3, so while there might not be a way to reset a specific conversation, you can directly edit the romanced or alive/dead values. Just follow this pastebin (and maybe this thread too) that shows you exactly which values you need to edit with the save editor.