If you're unable to e-verify a defective tax return because the option isn't appearing on the incometax.gov.in portal, it's likely because a defective return cannot be e-verified directly. The recommended solution is to file a fresh, valid return and then e-verify that. If you've already received a notice for a defective return and the e-verify option is still missing, filing a new ITR afresh and e-verifying it is the advised course of action.