I use the old but not forgotten Windows keyboard commands. I right click on the item in the taskbar and select move. Now I use the cursor keys to move it back onto the desktop.
Sorry if you've never learned to run Windows without a mouse but it is possible. PRACTICE, PRACTICE, PRACTICE this till you get it.
I usually have my XP laptop connected to a docking station and use a second monitor,keyboard,mouse.
The problem is if I shut down my computer with an app running in the second monitor, and remove the laptop from the docking station and try to bring up the same app later, it tries to go to the second monitor...which of course is not there...it is not configured in the Display control panel.
this is very frustrating as I need that app.