Google Drive is different from most other Google Apps in two ways: Google Drive has much more serious sharing and ownership controls than other Google Apps; Google Drive does not automatically empty its Trash folder. These two facts make Google Drive document recovery somewhat more interesting than restoring other lost Google Apps data.
Because Google Drive does not automatically empty its Trash folder—unlike every other Google App, which permanently deletes trashed items after 30 days—the first place you should look for a missing Google Drive file is the Trash.
You can find the Trash folder under the More link in the left column of Drive. Simply navigate into the trash, do a quick search for any missing Google Drive documents or files and see if your desired item turns up. If so, just select the checkbox next to the trashed item(s) and then click the Restore button at the top of the page. No muss, no fuss.
Things get complicated when a missing Google Drive file isn’t in the Trash. There are four likely causes for this, and only two of them are easily remedied.
Scenario 1: The owner revoked your access to the Google Drive document
If you aren’t the owner of the document in question, the only reason you can see it in Google Drive is because the actual owner shared the file with you. If the owner changed the sharing status to prevent you from viewing the file, the item will effectively disappear from your Google Drive.
The easiest way to check is to simply ask the document owner. If, however, you don’t remember who the owner is (or the owner has changed hands), a fallback is to search your Gmail for the message that informed you the original owner had shared the document with you. Just search Gmail for the document title and you should find it.
When you locate the email, just click the included Google Drive link and, if you are greeted with a message stating you don’t have permission to access the file, you know that the owner has revoked sharing. To regain access privileges, just click the Request Access link on the error page and the owner will be alerted of your desire to view the file. After that, it’s up to the owner to re-share the file with you.
Scenario 2: Someone renamed the document
If your missing document has been shared with multiple people and any or all of those persons has Editor or Owner privileges, it’s entirely possible that your missing document isn’t gone; it’s just renamed.
Again, the easiest way to check is to search your Gmail for the original sharing notification email. Just search Gmail for the document title you remember and then click the sharing link within. If a document opens, but it has a new file name, you know what’s happened.
Scenario 3: The owner relocated the document
This situation is a bit particular. A document owner moving a shared document around in their Google Drive folder structure wouldn’t normally affect your access to the file unless you were given access to a shared folder, rather than a shared document. In this case, you would have access to any item in the shared folder but, once the document is removed from the shared folder, your access to the document is removed as well.
Treat this scenario the same as someone directly revoking your access. Contact the folder owner and access him to restore your document access (or just move the document back into the shared folder).
Scenario 4: The owner permanently deleted the original
This is the Kobayashi Maru; the no-win scenario. If the document owner trashes a document and then permanently deletes it out of the Google Drive Trash, it is gone—forever. Google can’t get it back. To solve this conundrum, you’ll need to follow the example of one James T. Kirk and change the rules.
To restore a permanently deleted Google Drive document, you’ll need a third-party backup of your Google Drive data like Backupify for Google Apps—so you can enjoy the convenience of one-click Drive restore.