No longer getting emails via Thunderbird

Hello All,

I know this issue has popped up before for other.  I did look at some old suggestions and have tried them without success.  Everything with my Comcast/Thunderbird settup has been static for more then five years and then yesterday it just stopped working.   I can send emails via Thunderbird but it tells me because of network issues it cannot save a copy.  I get nothing in the inbox.   Comcast access via the normal web interface seems to be fine.    Any suggestions would be appreciated.