Issues with 500GB

I’ll admit that I’m not enormously computer literate, so I don’t have a whole lot of technical info to add on the issue. I’ve owned this HD for about two and a half years, and it’s never given me any problems up until the last few days. I noticed recently that it seemed to disconnect and reconnect without much provocation, but now that I’ve had more time to observe it, it seems like whenever the HD is trying to access a larger file or amount of files, it’ll shut down. Unfortunately, the state of the HD’s been degenerating pretty rapidly, and at this point, even trying to get into a folder will shut it down, and when the computer tries to Autoplay it, it’ll do the same thing. I have it disconnected completely right now, otherwise, my computer would be stuck in a continuous “autoplay then disconnect then redetect then autoplay again” loop, and that obviously bogs down my system. I switched out cables and tried it on a different computer, but it seems to be having the same issue regardless. There aren’t any noises that I can hear that are anything too peculiar. There’s a tiny bit of “churning”, but it’s done that since the day I got it and it’s never caused me any problems. My mother has the exact same HD as I do, she got it several months before mine, and hers is working like a charm right now. I’m concerned that the HD is dying, but I don’t want to dish out the extra money on a new drive until I’m certain of it. Plus, I’ll have to find some way to retrieve the files from the drive I have now. Any suggestions?