If you have a receipt or an order number from your original purchase, you can try contacting the support team of the current rights holder (usually Hasbro or the digital distributor). They may be able to re-issue a key if you can prove ownership.
One of the biggest issues with games from this era is that the digital landscape has shifted dramatically. The platforms that originally sold these licenses often no longer exist, or the developers have moved on to mobile app stores. This leads to several common problems for gamers:
