Hi
You will need to open up the sub where the power supply is located and see if there is a fuse.
It is possible that it has just blown a fuse.
If there is no fuse then the power supply is probably fried and this may have also taken out the amplifier and speakers themselves.
Unless you have the equipment and ability to fault find at component level it will almost certainly be cheaper and better to just purchase new speakers considering how cheap they are.