Drove my 98 blazer 4.3 hot now it won't start?

When you say you drove it hot, I'm assuming the truck overheated? If so, what the reason for your overheating condition? Have you scanned for codes?

check ignition module. on heat sink near ign coil. also another module inside distributor (cam posn sensor). if this module is bad neither spark or fuel will trigger. last culprit could be crank posn sensor on timing cover. (note this is on 95 blazer, with spider injector, and flat dist cap)