oppps battery was installed backwards

My husband put the battery in our 91 geo prizm this morning and accidently put it in backwards. He hooked up the cables and realised what he had done so he undid them we did not try to start the car with it in that way. Now the lights come on when you turn the key one but it won't even turn over. Any ideas would be greatly appreciated. We have a battery charger and we know the battery is fried but there was a little smoke at the alternator area also.

I think your in deep doo-doo. You may have damaged the charging system and the main computer.

Have it towed to a competent garage

You probably fried the diode bridge (rectifier) in the alternator and shorted the stator, in which case you need a new alternator. If you are extremely lucky you may have just blown a fuse, but I highly doubt it. The wires that run between the battery, alternator and battery junction box have fusible links, check those first.

check your fusible links at the starter and the battery!

most of the prisms have a set of fuses on the positive side battery cable check those and check the main in the fuse block under the hood on the driver side, i also agree with checking the fuseable links and have the alternator tested. auto zone and advance auto will check then for free