I deleted Dispenser 76 agent, becouse he was offline when the web page said security code required and now i can't add the bot back.
Please help.

On the authentication code page there is a button which says 'add bot' try giving that a press and hopefully you'll get the bot back on your friends list. You may then need to log out and start the process again to get a code but it should work.

If the bot ends up being stuck in your invites sent section of your friends list or if the bot is 'ignoring you' you need to find the steam community page for the bot, block all communication and then unblock and start the process over and this too should solve your problem.

Thank you! Fixed!