I know the recovery method of oversized attachments in expired QQ mailbox: pc recovery method: If you don't have the habit of emptying the recycle bin, you can look for them in the recycle bin and right-click to recover.

If the recycle bin is empty;

You can use the data recovery tool for recovery. If you can't operate it yourself, but the file and it are very important, you can ask a special data recovery person to help you recover it.

The easiest way is to ask your friend to resend the file.

Learn to back up important files in time. Otherwise it will be very troublesome to lose it. Using QQ Weiyun and other network disks is a good backup method. Particularly important files can also be burned on CD (around 5 yuan, an empty CD).