Recover permanently deleted files.

Google Drive

Missing on my Google drive.
Open google drive and then open google drive help center.

 Help center link :
Click Here

1.At the top left, tap menu click.

2.Then click Contact Us. 

3.Then select missing or deleted files. 

4.Then select one option. ( chat, call, email ) 

The question should has as much details as possible. Don't expect them to provide you with an immediate solution of your problem; moreover, not in all cases Google Drive experts are able to help to recover permanently deleted files.