1991 Buick Park Avenue wont start

Welcome to the forum, have a helper crank the vehicle, while you check for spark at the plugs. You can pull plug wire loose, stick known good plug in the boot, lay metal part of plug against metal part of engine, have helper crank it, while you watch for spark at the tip of plug. Check for trouble codes.

, turn key on, no crank, place jumper wire between terminals A & B of the datalink connector. The check engine lite starts flashing, you count the flashes to get the codes.