click on get messages on thunderbird. You won't mention email service, software u are using but i think it is thunderbird. Click on get messages on the top hope it helps.

I am using Thunderbird as email service. IT docent help to click on get massages. I have had Thunderbird for 2 yeares and never had any problem before. This problem started yesterday. I cant receive messages but i can send messages but the messages are not saved.

https://support.mozilla.org/en-US/kb/problems-sending-and-receiving-messages

I removed my password and restarted Thunderbird and was avsked for new passwords but it didnt work so I asked my ISP if they had any problem but no problem.

Verify your password using webmail.

your email service provider i.e. on which website or server you have account and it still allows POP3/IMAP?