Sure. To reopen a closed project you just need to go to “closed projects” (3rd icon at the top of the project organizer, so left of the page, close to the main menu of the application).
There you just need to select “open project” by clicking on the “actions” icon on the right of the project name. You can find this “actions” icon next to the project name in the project tree on the left, or in the working area.