We just had an A/C repair man working the Air Con when he flipped the wrong circiut switch and caused a blackout, when I turned my computer back on my PC running Windows XP SP2 wouldn't read my external drive and it was making a clicking noise. All computer repair stores charge at around $60 just to look at it, so is there anything I can possibly do before taking it in ?

No.

Really, I'm not being a smart-ass. If $60 is over your limit, your choices are very limited. It's impossible to tell from a quick description, but I'd guess it's likely not within the limits of an average Computer Tech anyway, and you'll likely be blowing $60. They will either send it to a professional Data Recovery company, or they will try it themselves, and likely make things worse or impossible. If the data is important, send it to a professional. If around $500 is too much, you could try taking the drive out of the external enclosure, and connect it inside your computer. You can also try booting your computer with Knoppix and see if the drive mounts. If these are above your abilities, then you're out of luck.

I found a different USB cable, and now it comes up in Device Manager under USB Controllers as USB Mass Storage Device but it has an exclamation mark. I still have the disk with the drivers it came with, so what would happen if I uninstalled it and reinstalled it with the drivers? Would that be the same as formatting and will I then lose all my files?

If its knocking on Samsung 90% u got MHA problems´s , need to be tried by a DR company

Best Regards

Ditto to what Beto said. As to your question, it should be safe for your data to uninstall and reinstall the drivers. Just be aware that the longer the drive is running, the more potential damage you can do.