94 Burban getting nothing

my ma said she drove it all day, then turned it off when she picked up he kids from school. when she came back she got nothin. I thought it might be the starter so I changed it. problem is all im getting is headlights and interior lights (both bright).Nothing else works the windows are down ,no power locks no radio no nothing. when i first put the key in ,I heard the dinging from the ignition .after one attempt to crank no more dinging. IT wont spin over.
how can i tell if my IGnition switch is bad?

Check your battery connections. If everything works until you turn the key then come back on after you turn the key off your losing continuity. The most likely place is the battery connections to the battery cables.

Ive just put in both new cables . still nothing. a local guy told me i could jump the windows up using my test light. havent tried it yet, but it looks like rain here tonight.
after i turn the key the first time nothing comes back on. ive also installed a 800cca optima batterytill nothing. Thanks for the quick reply. ill keep at it.

Just to re-cap. New battery cables (both pos & neg), new battery and new starter.

These ign sw's have 5 different contacts in them to power different circuits and are prone to failure.

What happens if you turn the headlights "on" and try to crank? If they go out, wiggle the pos & neg batt cables, as even though they're new would be the most likely cause for the headlights to go out.

Also, with the ign sw "on", check all fuses for power thru each fuse.

You might check your alternator plug in for voltage on pin 1 it usually feeds the ignition switch an prob the fuse box also.I know there are more than 2 connections on newer alternators and not sure which pin they use may also be 1.
Bruce suburban with 427 truck motor and u think u got problems...haha