You are confusing me

Props are added in levels, which are saved on your hard drive somewhere - you have to select the location.
Triggers and doors are added in areas, which is saved within the toolset database.
It sounds as though you were working on areas rather than levels since the Open Recent doesn't list them. If they were areas, they would be in the palette. If you don't remember the name, easiest way is to go to the Area selection, click on the down arrow to the left of the text box and check 'Only show resources checked out to me'.
You should be able to narrow down the area you were working on from there.