TFS 2012 : The working folder is already in use after Hard Disk Format

I'd suggest using the (free) tool TFS Sidekicks: http://www.attrice.info/cm/tfs/

This will give you a GUI to view all workspaces (across all users and machines), and delete the obsolete ones.

This is stored on the server, but the tf workspace command should be able to remove it for you. You will probably need to supply it with the correct machine name to find it:

tf workspaces /computer:* /owner:domain\jesse.houwing /collection:http://yourserver:8080/tfs/DefaultCollection

Find the missing workspace (the one that was formatted) and remove it from the server:

tf workspace /delete /collection:http://yourserver:8080/tfs/DefaultCollection workspaceName;domain\jesse.houwing

Do not confuse tf workspaces /remove and tf workspace /delete, the former only removes the registration from your machine, the second removes it from the server.

Or, if the computer name and the username have stayed the same, edit the workspace and delete the paths no longer valid (or update them to their new location) by changing the workspace configuration. Use

tf workspace workspaceName;Owner

to open the dialog to edit your current workspace.

Or use

tf workspaces /updateComputerName /updateUserName

To reassign the workspace from the old computer (iinstallation) or user to the new one.