I just started having trouble sending emails...anytime I try I get a verification page where I need to enter a code but the page doesnt allow me to enter it. Its only on one of my yahoo adresses, the other two on my computer are working great...HELP!

go to AOL.com and do it there we are not AOL.com

enter your email address to login, and click on the "Forgot Password" link. It will either ask you your security questions, or send you a link in an email, which will allow you to select a new one.

Click the "Need help?" link on the Gmail sign-in page.

They should have a caption that says,"forgot password?" underneath the login. click on that and they will send you a link to your email with a temporary password. write it down than click on the link and it will go to a page asking for your old password. put in the password they gave you. below that it will have a space for a new password. Put the password of your choice in that space. then click done. they will then they will send another email to you showing confirmation. I hope this works.

A verification code will be send by Google, when you have set a two time verification to your account. It will be normally send to your mobile phone. It will contain digits only. When you try to ace's your account, by entering your email address and password, the window will ask you the verification code. Just open the message that you've got from Google, and enter the digits you see there, as it is; and press 'Enter'.
It is a security measure against unauthorized log in to your account.
To turn off 2-step verification:
> Visit the Using 2-step verification page under your Google Account settings. Sign in with your username, password, and verification code if prompted.
> Click the "Turn off 2-step verification" link.
> A pop-up window will appear to confirm that you want to turn off 2-step verification. Click "OK".
Reference:Turn off 2-step verification
Gopakumar Gopalan Google

You can combine multiple Gmail accounts into a single, primary Gmail account by using the POP3 Mail Fetcher application built into Gmail.
The Mail Fetcher enables you to retrieve email from POP3 email accounts, including Gmail, and send mail as if from a different email address all from within your primary Gmail account. Configure your primary account to manage your other Gmail accounts with the Mail Fetcher.

Sign in to the Gmail account that you want to use to manage your Gmail accounts.
Click the "Settings" icon, represented by a gear cog, in the top left and click "Mail Settings."

Click the "Accounts and Import" tab.
Click the "Add POP3 Email Account" button.
Enter the email address of your secondary email account and then click "Next Step."
Enter the password of your secondary email account and then click "Add Account."
Click the radio button beside "Yes, I want to be able to send email as
[SECONDARY EMAIL ADDRESS]" and then click "Next Step."
Enter the display name for your secondary email address and then click "Next Step."
Click "Send Verification" and then check your secondary email account.
Click the link contained in the verification email to confirm the integration of that account with your primary Gmail account.
All mail sent to your secondary Gmail is now delivered to your primary account, and when responding your secondary Gmail address is displayed in the From section of the email.

Access all your gmail accounts

1. Go to My Apple ID (appleid.apple.com), click "Manage your Apple ID", and sign in.
2. If you have two-step turned on, you'll be asked to send a verification code to the trusted device associated with your Apple ID.
   
3. In the "Apple ID and Primary Email Address section," click Edit.
4. Enter the email address you want to use, then click Save Changes. Apple will send a verification email to that address.
5. Open the email from Apple, then click Verify Now in the email.
6. When the My Apple ID page opens, sign in with your renamed Apple ID.
7. If you have two-step verification turned on, you'll be asked to send a verification code to the trusted device associated with your Apple ID.

After you see a message indicating that verification is complete, remember to update all of the features and services that you use with your Apple ID.