E-mail folders have disappeared
I have a cox.net e-mail account. Yesterday Cox had a service issue and I had no e-mail for several hours. When it came back up the mail folders I had on my iMac to organize different items had disappeared. The folders are still on the Cox webmail system if I go through the Cox website (very cumbersome) but they've disappeared from my iMac. Cox is an "imap" e-mail server (not sure what that means). Any idea how I can get the folders back onto my iMac? I'd really appreciate any help.
Thank you.
iMac 21.5", macOS 10.15