My upper abdominal pain improved days after celiac plexus block with alcohol but returned 2 weeks later. does that mean it didn't work or wore off?

Unclear: Typically when a celiac plexus is performed, the effect is immediate. The local anesthetic can last 24 hours, and the effect of alcohol will ideally supercede that for about 6 months. If you had no immediate effect and no relief for a few days, it was likely another effect- not the block. This could have been from a steroid, for example.