HD not recognized by computer

My HD worked perfectly for quite some time and then it was no longer found in my computer.  In order to fix mine I downloaded software from: http://www.file-recovery.net  and this corrected the problem.  This software costs $35 up and will fix the HD and recover all files. 
Western Digital offered to replace it at no cost under warranty but then I would have lost my pictures I could not replace.  It may have been my fault for not clicking the remove safely before unplugging it but there were no instructions telling me top do so.

All the .pdf manuals for all the USB drives specify to “Safely Remove” the drive to avoid corruption/data loss, as far as I can tell.