There are several ways to go about it. If you do not know their account name but you know their character name you can do : [global interface where playermobile name = "John Doe" : however it will bring up all characters named John Doe. The quotation marks are only necessary for names that contain spaces like the provided example.
If you know the general area in which they logged out you can do : [global interface where mobile logoutlocation >= (1300,1200,0), logoutlocation <= (1310,1210,0) : to search all tiles within those two coordinates, although it will show anyone who is/was logged out in that area even if they're currently online. If you use the custom script Text Input, which I believe is available to download somewhere on this website, you can expand the command further to narrow it down even more to include map = internal and their name, etc.
The interface menu that comes up if it finds a valid target allows you to access the player's properties, bring them to you, go to them, etc if you click the arrow next to their name.
**Edit**
Fixed typo.
**Edit 2**
Also, yes, [props does work to bring up a property menu for all items, statics, mobiles, etc.
**Edit 3**
Here is a link to the TextInput script that will triple or more the available text you can enter for commands and other text.
Ever been making a custom item using "[add set " and get frustrated having to wind up [Props the item to get everything put in? Well fear no more! You can now get a lot more text put in with this. This on [TextInput will...
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