I'll start off with some information about my USB. I use a SeaGate external hard drive USB with 1 TB. About ~250 gb of it is partitioned and formatted to create a Time-Machine compatible partition. The rest of it is just a normal partition, formatted exFAT, which I use to store data.
I use a 2013 Macbook Air on the latest version of Yosemite.
This drive was working fine until last night, when I attempted to resize it (with iPartition, so I could keep my data) to give the Time Machine Partition just a bit more room. It seems to have worked, but immediately following that OSX gave me a message saying that the larger partition (which I called MISC) was unable to be repaired and should be backed up and reformatted (or something along those lines) ASAP. My Time Machine partition (which I called OSX) seems to be working properly, but I haven't made any new back-ups since then. As far as I can tell, this would not have happened without the iPartition, but I can't be sure.
I really do not want to lose all my data, since I have no way to back up. This is my only large USB and my hard drive is too small to contain the data I had there. So, I am currently trying to use Drive Genius 3 to repair it (only MISC, but I'm fine with it if I can only repair the entire hard drive at once) WITHOUT losing my data. However, it seems I'm not able to repair it because it's set to read only (this was said in an error message given by Drive Genius). I checked the MISC partition using the "Get Info" tab, and it seems that it is set to read only. However, I'm unable to change permissions. I'm pretty sure this is due to whatever caused OSX to give me the message saying that it was unable to be repaired (Disk Utility gives the same message; it also said something like, "You are not able to write to this drive"). It only says something along the lines of, "You may only read this drive." When I get home, I will provide more clear quotes. It doesn't give me options to change the permissions, so I can't just do that.
My questions are: 1. How do I change the permissions on the MISC partition? I'm ok with just forcing this through Terminal if that would work. a. Would Drive Genius actually be able to fix it? Because if not, then there's no point in trying. 2. Are there any other ways to fix this problem without losing all my data? a. Note: I'm fine with losing my OSX partition's data, because I can just make a new back-up (and also that partition works fine and doesn't have an error message).
If I can't do this using Drive Genius, unless you guys give me some other possibility, I'll try to use testdisk 7.0 for the task. I'm not quite familiar with it, so if anyone has experience with it that would be greatly appreciated. Failing that, I'll simply have to do it the regular way that involves losing all my data.
I'm really terrible at a lot of this stuff, so I'll need a lot of handholding unfortunately. Please provide screenshots if possible (and I will do so as well!) for your instructions, especially if it involves Terminal, but mostly for anything. If you know of any programs that might be able to do this, even if they cost money, please link them to me!
Thanks for the help!