My sister put the battery backwards and now it doesn't do anything

SPARKS went off,didn't they?don't see how that happens,but it does from either not knowing or not paying attention!changing a vehicle battery should be the first test at the DMV before drivers license are issued!check ALL the fuses with a volt meter.you may have got lucky and only have fuses blown.i saw this happen on a Sonata one time.they took it to THREE different dealerships,and it never ran again,could not be fixed! the person that did this had to buy the person another vehicle.NO,not the person had to buy,it was Autozone that had to buy another vehicle,because that's where the guy worked that put the battery in backwards!!!