I purchased a Crysis+CrysisWars+Crysis Warhead CD/DVD a long time ago (looking at around 10 years here) and now the key isn't working. I contacted the company and they didn't help me. What should I do?
If this is on Steam, have a look at the redeem FAQ page that outlines what you can do.
Especially the section regarding "Invalid key"; which states:
If you are still receiving an invalid error, we encourage you to contact the retailer for further assistance.
If the retailer is unable or unwilling to assist you, it is recommended that you contact the game's publisher for further assistance.
If none of the above helps, you're probably out of luck. Thankfully Crysis is often on sale on places like Steam and GoG for cheap.