Email on my iPhone

Please help! Yesterday I started getting error messages when I tried to get my email off my iPhone. I followed the instructions regarding entering my password, and it still didn’t work. I absolutely must be able to access my email from my iPhone. I understand a lot of people are having this problem. If anyone can tell me how to get access again to my email from my iPhone in a step-by-step manner, I would greatly appreciate it! Thanks in advance!