Only the user who checked out the file on that lost computer can check it back in...from that lost computer. LOL
The only options are to destroy it or undo the check out.
Login as the administrator, right click on the checked out file, click "Undo checkout".
When the undo check out dialog appears, click the "Undo checkout" checkbox and click OK. Notice the warnings column.
When the undo checkout happens, you will probably see a warning that the file was checked out on another computer or the file cannot be found. Click Yes or Yes to All.
In this scenario, that's about the best you can do.
Oh, I did not noticed that check box for Undo Checkout, no wonder the undo wasn't working for me. I had to delete the file.
Thanks for the help.