Can't get inbound or outbound mail

I have THunderbird version 78.11.0 installed on 2 windows 10 computers. I'm using 2 accounts - yuri101@prodigy.net and yuri@prodigy.net. Both accounts are using the same inbound/outbound servers. Today suddenly one of the accounts on both computers can't receive or send any emails. I'm getting message that password on inbound.att.net and outbound.att.net are invalid. Settings are the same for both accounts, yuri101 is working OK, yuri is not working. I can login to att.net with yuri@prodigy.net and it's working fine. Under save passwords I see the same entry for both ids. How can I fix this issue? Thanks a lot, Yuri