Deleted mails from GMail

Hello,

A number of my gmails from Feb & Mar 2015 appear to have been deleted from my "All Mail' category. I am trying to recover them. In the forum somebody from 'Solved' says :

you can recover permanently deleted emails even after deleting them from your trash folder all you have to do is open you gmail then click the drop down arrow from your search box at the top of the screen. it will then ask you several question such as to: or from: subject, has words or date with in. don't answer any of these question just click on the blue search button on the bottom left of the search box and all of your deleted emails will be revealed.

Tried this but cannot get to the drp down arrow from the search box. All I can see in the top right hand corner is the 3 line icon for the drop down menu. That does not give me the option mentioned above.

Very grateful for any help on this.