I'm betting the power circuits in the drive enclosure are fried, if not the drive itself.
Before you consider binning the drive I would remove it from the enclosure, this may be relatively easy or hard depending on the enclosure and will void any warranty, but as you've fried the drive I'm guessing the warranty is void anyway.
You can then install it internally using the appropriate connections IDE/SATA depending on what the actual drive is, if it's a fairly new drive chances are it's a SATA. If it works you can leave it as an internal (it will work faster) or opt to buy a drive enclosure for around £15 and use it externally.
I had 2 Freecom 250GB drives fail a year or so ago and they now work in Icybox enclosures.
i bought a new enclosure, but still not working, so i suspect the drive is damaged. is there any way to repair it? because my drive is 1tb, so there are alots of data in there (which is mostly videos).