Hi, hope you're doing well. I’m Ian, an Independent Advisor and Microsoft user like you. I’m happy to help answer your questions.
I'm sorry to hear about this issue.
Files that you share in a channel are stored in your team's SharePoint folder. Which can be found in the Files tab at the top of each channel.
Files that you share in a private or group chat are stored in your OneDrive for Business folder and are only shared with the people in that conversation. These will be found in the Files tab at the top of a chat.
Note: The OneDrive files you see in Teams are OneDrive for Business files associated with your Office 365 account—not your personal OneDrive. Teams can't currently connect to your personal OneDrive.
https://support.microsoft.com/en-ie/office/file...
I hope this helps, but please let me know if you need anything else.
Regards,
Ian