Help Getting EOS

Back in 2017 I bought some EOS coins. At some point they did something and it changed where those coins are accessed. I believe they moved them to their mainframe or something?? Not sure. I have tried a couple times to get control of these coins but to no avail. Is there anyone who may be able to help guide me on how to get them? Claim them? Was wanting to move them to Coinbase. I am admittedly not educated much on this matter but I have moved varying types of crypto in the past so do have a base knowledge. Thanks to anyone who can help.