The link to electronically file your return will not be visible if your return is not ready to electronically file.
This indicates:

• You selected No to the question "Do you intend to file this return electronically?" on the Filing Options page under the Step 1 of the Steps to File page.

OR

• Your return does not qualify for electronic filing.

To view the reasons for failure to qualify, as well as other possible errors in your return, click on Step 2, Review summary and check for errors, on the Steps to File page. This can be accessed by selecting Review Return located at the bottom of any page.