Receive e-mail but cannot view contents. They just say "Loading". My wifi is working, as I can get on the internet.

What is your mail client and who is your mail provider, and if you are not still using 10.5.5, what version of OSX are you using?

What is your Mail client, Mac Mail or something else,

Does your email address end with @me.com, @icloud.com or @mac.com

Go to System Preferences>iCloud and sign out, reboot and sign back in.

You're welcome