What if I don't know the cost basis of my cryptocurrency?

Hello there, I'm curious about a potential issue that many cryptocurrency investors may face. What if, for some reason, I'm not entirely sure what the cost basis of my cryptocurrency holdings is? How does this impact my taxes or overall financial planning? Is there a way to calculate or estimate this cost basis if I don't have the exact records? I understand that knowing the cost basis is crucial for accurate tax reporting, so I'm eager to learn more about how to navigate this potential obstacle.