Do you have voltage on battery? You might have made a short that killed it.
If yes, the voltage is there, check after battery - between ground and e.g. starter cable or fuse No. 1.
If no voltage - check the battery connectors (sometimes they crack when you screw them too tight). Check the ground - the main one goes from battery terminal to the left wheel arch, right next to the battery. Check the positive - please note the car is getting power from starter connector, not from battery connector. Have you hooked up all the wires hanging around the starter properly? The supply goes from starter, through alternator and lights switch. If you missed the connection at the starter, you do not have power.
If you say EVERYTHING is dead - by this time you will probably spot it.