Fixed: Failed To Open Virtual Machine/ This Virtual Machine appears to be in use.
Step 1: You need to browse through, where your virtual machine is located, which will be shown on the error page itself.

Step 2: After opening the target virtual machine folder, you have to find to find all the folders with extension (.lck).

Step 3: In third step, you need to delete all the files with (.lck) extension.

Step 4: After deleting all the files, open the virtual machine as usual.

Step 5: You will be able to run the virtual machine without any error.

Video: How To Fix “Failed To Open Virtual Machine” Error
If you have any problems in following the above mentioned steps, you can watch the youtube video embedded below.