I have a 91' Corolla that ran without problems up until a couple weeks ago. I just replaced the battery because the old one died, and it worked fine for a while. Now, it won't start or do anything. I turn the key and there is nothing. The radio and lights don't work, and jumping the car doesn't help at all. I'm guessing there's a bad connection somewhere in there. I know the battery is fine, but it's not giving any power. Any help would be appreciated.

same thing happened to me check the mean fuse on the positive side of the batery before you replace it find the sort

Yup. check all your fuses