Can't build standalone app after eject


I published the application in the play market via expo. Now i have the keys saved in the .jks (java keystore) format. I did the expo eject, but now I can’t even run in the simulator, so I dragged the entire project to react-native init. It says that you must first generate the keys, but they are stored in the .keystore format.How build apk file using old keys(.jks) and update app in play market?And with ios I have same problem.
Who had the same problem?