The address tab must've been hidden. Try to go to View > Show Addresses and you should now be able to see the tab. Also, this applies to other tabs such as 'Coins', 'Console' and 'Contacts'.
Also since you want to access the private keys of addresses you can alternatively do this as well: Wallet > Private Keys > Export and this should show every corresponding address generated in your wallet with their private keys.
Thank you for your replying, but unfortunately menus View and Wallet are absent on interfaces of Electrum new versions for Linux. It's inconvenient for using on OS of Linux. I think it's possible to unlock hidden tabs 'Addresses', 'Console', 'Contacts', but in standardized install of wallet I can't unlock hidden tabs.
Who can help me in solving this problem?