How can I see a list of texts, calls and/or emails on a given phone in my account?

Log into your account and go to the usage section. Your logs have calls and texts, not emails.

I know that I sent text messages on a certain day and they are not showing up. Any suggestion to why? They were in a group text and all parties have iphone on my plan. It doesn't show on anyone's log of texts.

If all phones were iPhones, it was probably sent as an iMessage. You can look on your phone to confirm. If the color of the sent text bubble is blue, that’s an iMessage. iMessages are not in your text log because iMessage is Apple’s messaging system.

Do you know any way to look that up? I need to show someone proof that messages were not sent at a specific time. Just showing my phone, they could say I deleted the message.

As @sandblaster mentioned, if they were sent as iMessages, they will be on your phone, color coded, and if they are all green, they were sent at iMessages and won't be on AT&T's system. There is no way to get a "listing" of iMessages sent/received from Apple.

If you deleted from your phone, there is no other way to prove when sent.

Why are calls blank on my data usage report