Were you able to recieve and send emails earlier?
If so since when are you facing this problem? Is it something after bringing any changes into your machine or installing any applications?
Just for confirmation let me be brief about the configuring gmail in outlook.
1.) Enable POP3 mail in gmail:-
>Sign in to Gmail.
>Click Settings at the top of any Gmail page.
>Click Forwarding and POP/IMAP.
>Select Enable POP for all mail or Enable POP for mail that arrives from now on.
>Choose what to do with your messages after they're accessed with your POP client or device.
>Configure your POP client* and click Save Changes
2.) Configure your outlook:-
>Enable POP in your email account. Don't forget to click Save Changes when you're done.
>Check the Tools menu, and select E-mail Accounts...
>Click Add a new e-mail account, and click Next.
>Choose POP3 as your server type by clicking the radio button, and click Next.
>Fill in all necessary fields to include the following information:
Your Name: Enter your name as you would like it to appear in the From: field of outgoing messages.
Email Address: Enter your full email address (firstname.lastname@example.org or username@your_domain.com)
Google Apps users, enter the server names provided, don't add your domain name in this step.
Incoming mail server (POP3): pop.gmail.com
Outgoing mail server (SMTP): smtp.gmail.com
User Name: Enter your Gmail username (including @gmail.com). Google Apps users, enter your full address in the format username@your_domain.com
Password: Enter your email password
>Click More Settings... and then click the Outgoing Server tab.
>Check the box next to My outgoing server (SMTP) requires authentication and select Use same settings as my incoming mail server.
>Click the Advanced tab, and check the box next to This server requires an encrypted connection (SSL) under Incoming Server (POP3). Enter 995 in the 'Incoming Server' box.
>Check the box next to This server requires an encrypted connection (SSL) under Outgoing Server (SMTP), and enter 465 in the Outgoing server (SMTP) box.
>Click Test Account Settings... After receiving Congratulations! All tests completed successfully, click Close.
>Click Next, and then click Finish.
>Download the latest updates for Outlook from Microsoft. This will help prevent the most common Outlook errors Gmail users see.