Hello Xiaolufer, and welcome to Seven Forums.
See if dragging or moving the Recent Items on your desktop back into the
C:\Users\(User Name)\AppData\Roaming\Microsoft\Windows may help.
If not, then make sure that the registry (regedit.exe) locations below have the correct path for the
Recent expandable string value in the right pane. If not, then right click on
Recent, click on
Modify, enter the correct path, and click on
OK. Afterwards, restart the computer and do what you have in the quote box again to fix the Recent folder.
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
(Use the same path, but substitute
User-Name in the path with your user account's name instead.)

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
(Use the exact same path as below for Recent.)

Hope this helps,
Shawn