Car doesn't start

If the battery is good then you must have some connection problem somewhere.
Be sure the connections are clean and tight.
Connect the battery and check accross the terminals with a meter or test light to be sure that you actually have power.
Remove the cover on the fuse block and check the main power feed from the battery. Top right in the fuse block there should be a large cable coming in to feed the fuse/relay block. Check that.
Maybe a bad connection or cable it sounds like.

Do you have power to the cable I mentioned in the fuse block itself?

If you have a meter, check from negative to postitive on the battery to verify voltage.
Then keep the black lead on negative and touch the positive lead to where the cable bolts to the fuse block in that upper right corner.
(make sure you are set to measure DC volts)
You should have the same voltage there.
If not you might have a cable issue.

No lights come on or anything at all inside the car?
The headlight switch won't turn the lights on?
No chime when the key is put in the ignition?

It sounds like a blown fuse link, those little square fuses with copper inside them. Look them over closely to see if any look damaged. They are hard to see sometimes.