my spreadsheets are disappearing on my devices

Hello, thank you for reaching out to Microsoft Q&A.

1. May I please know where exactly you are saving your Excel files? Are they stored on your local drive or in a cloud storage service like OneDrive?
2. Have you checked if other files from the same location are accessible?
3. Are your spreadsheet files shared with a group through your organization's SharePoint?

If you are editing Excel files in the Excel app on your Android device (as you have posted the question on Android Excel forums) and have your Microsoft account linked, your files are usually saved directly to the cloud, such as OneDrive by default, especially if autosave is enabled.

So, you can sign in with your account on https://onedrive.live.com/ and check your recent files in the Home tab. If not, check other folders like the documents or the recycle bin folder and see if you can recover the lost files from the folders.

If Autosave is enabled, make sure your device is connected to the internet and that the connection is stable.

Let me know if you still need more help.