If you're trying to recover an InDesign file that you've accidentally deleted, didn't save properly, or that's been corrupted, there are a few methods you can try:

1. Automatic Recovery: InDesign has an automatic recovery feature that you can use in case of crashes. If InDesign unexpectedly shuts down while you're working on a document, the program attempts to recover all work up until the last automatic save when you start it back up. If the program doesn't automatically prompt you to recover the document, you can find the recovery data file in a hidden folder on your computer, usually located here: Users/[User Name]/Library/Caches/Adobe InDesign/Version [#]/InDesign Recovery.

2. Backups: If you've been regularly backing up your data, you can recover the file from your backup source. If you're using a cloud-based backup service like Dropbox or Google Drive, you may even be able to recover previous versions of the file.

3. Temporary Files: InDesign, like many programs, creates temporary files while you're working on a document. If your computer hasn't been restarted since you lost the file, it may still be recoverable from the temporary files. These are typically located in the same folder as the recovery files, mentioned above.

4. .idlk (InDesign Lock) files: When a document is opened, InDesign creates a lock file with the same name as the open document. If InDesign crashes, the .idlk file may still be in the same location as the saved document. While you can't recover your document from this file, its existence can prompt InDesign to attempt to recover the document.

Remember, the best way to prevent lost data is to regularly save your work and keep backups. Some people recommend following the 3-2-1 rule: keep at least 3 copies of your data, 2 of which are locally stored in different devices, and 1 copy stored offsite (like on a cloud service).

Please note that the paths and steps might vary depending on the version of InDesign and your operating system.