Project Recycle Bin keeps only delete forms. It is accessible just for Project Administrator which can restore forms if necessary.

Restore forms from Recycle Bin

 5.  Log into the project as a PM.

 6.  Click Recycle Bin in Tasks section under Main module.

 7.  Select forms using the checkbox from the left side of the Form ID and click Undelete button

 8.  The forms are restored. Flat forms restore keeping the Form ID. Tree forms restore in the first position available in tree, so the Form ID may change depending on this position.