During the format, the mac accidentally got unplugged and on restart hd setup doesn't recognize it again.

Click to expand...

If this was during the low-level format then you are likely to have turned your drive into just a curious lump of metal and plastic.

There are two times when loss of power can be fatal to hardware...

i. low level format of SCSI drive

ii. flashing of system eeprom

I think you may have hit case i.