E-filing deadline is midnight October 17. If you do not e-file by then, your tax return will have to be sent in by mail. Mailed tax returns are taking six to nine months to be processed by the IRS, so if you are getting a refund you will have a long wait if you have to file by mail. So you may have a choice of e-filing on time--incorrectly-- or waiting for all of your information and filing by mail if you cannot come up with the investment information in time to e-file.
If you file it incorrectly without all of your income, then you will have to amend. Amended returns are taking just as long---or longer-- to be processed by the IRS.
Have you tried going online to get the investment information again instead of looking for what you may have done with it in your home?