My email account is not working. I can’t send, reply or forward any email. I can only open email

I have been trying to get this resolved for weeks. I can't send, reply, or forward anything. I can't change the font size or style. When I try to compose, reply or forward, the page that comes up is frozen I can't even put the cursor down in the body of the email box.  I have had this account for many years and I have a lot of documents, pictures and other media saved in my folders. I can't forward any of them to a different account I had to set up because of this. Please help!!!!!