Can you confirm the engine turns at all - even manually? "Vapor lock" - what is or was causing that concern?
Too much unknown to offer any advice. Seek local guidance at a shop near you. Here's a way to look one up:
www.repairpal.com/repair-shops
RepairPal Certified shops can diagnose and repair your 1999 Buick Century. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.