Egas ute wont start after changing plugs?

[Day-mow]

a friend came over to change plugs this arvo. the plugs we took out where pretty average but iridium but they looked like they where to far into the cylinder head. there was a few mm that was like rusted a few mm that was stripped and then the rest of the thread was fine.
put new platnium plugs in and the car wont start. whys this?

i checked i have spark and compression. but cant hear a click when we turn the key over from the Gas mixer. is there a fuse i can check or something i may of knocked out.

i've loaned the friend my work car but i really wanna get this sorted. any help would be good. thanks so much