my icloud email is not working

My email on icloud using my friends phone, my decktop pc, my ipad,my iphone 5c is not sending or receiving emails ! Please Help??

1. I have shut down and logged out of all devices - still no go
2. I have back up all my apple devices - still no go
3. I have deleted my email icloud accounts on my iPhone 5c and iPad still no go
4. I have reset my my iPhone 5c and iPad still no go
5. I have got my friends to email me and the email does not work - sent back saying " Failure Notice"

Please Help