I did an 'offline' defragment with O&O, which basically defragments the page file, etc. When I restarted, chkdsk ran and deleted all the references to where a large portion of my data was, and now I can't access or find the data, but the hard drive space is still taken up. Is there any way to recover the files? They're still on my HDD, I just can't get to them at all.
Yup... defraging the page file is a slightly dangerous operation. You need to do some sort of recovery, start by NOT using that PC as any data written to the drive may prevent recovery. "Jsut losing the pointers" is the equivalent of deleting the data, all data is is a bunch of pointers to the start location, without that there is nothing there as far as the OS is concerned.