There may be an easier way, but this was a quick way to find ALL the checked out files in TFS, something I needed so I could make sure no one from the data team had anything checked out prior to some consolidation/maintenance. The “Developer Command Prompt for VS2012” resolves to C:\Program Files (x86)\Microsoft Visual Studio 11.0 on my machine. Change the output file location to something that makes sense for you:
tf status $/ /USER:* /recursive >C:\ANDY\checkedoutfiles.txt
If you just need a files for a single user try this; http://kenyontechnology.com/2013/10/29/how-to-find-all-checked-out-files-in-tfs/, I used it to get a start on the minor tweak above, and there are a bunch of other switches for tfs.exe, the ones for status can be found here: http://msdn.microsoft.com/en-us/library/9s5ae285(v=vs.100).aspx.
I managed, just, to resist the urge to figure out the query instead.
Will come in handy I’m sure, the biggest thing we found was SSIS projects checked out when someone needed to change a parameter before running.