i cannot send emails.

i received an email from att to switch to the new att email...i confirmed the switch...

If you got such an email it wasn't att who sent it.  It was a phishing email and you should not have clicked anything and should have trashed it.  So now you need to check your email settings to see what may have been changed.  Below are my standard list of things to check.

• Change your password and security questions. The link I supplied allows you to change the password three ways; using your security questions, using your recovery email address, or by snail mail.
• Log into your webmail through start.att.net and click the settings gear->more settings. In there you will see a number of commands on the left. The ones that need checking are Mailboxes, Filters, and Security and Privacy.
• Mailboxes. Click that and choose an account in the Mailbox list to bring up that account's settings panel on the right. Check the Reply-to address and see if it is suspicious. Blank it out if you don't want that set. Check the forwarding setting and make sure it is blank or what you want. Check the other settings there as well. When you are done click the Save button at the bottom to update that account's settings.
• Filters. Look for suspicious filters and subtle filter names like '.' (a dot). Remove them and click the Save button.
• Security and privacy. Make sure no addresses are defined who's email you don't want blocked. Click Save to update those settings.
• Contacts list.  While it doesn't affect the running of the webmail it's still good to check to see if everything you expect is there.