how to recover files deleted by ccleaner from the trash?
No version of CCleaner has any sort of undo functionality - this would essentially defeat the purpose of the software by preventing it from reducing the amount of space used on the device, and make it so that these 'undo files' would contain the same personal data you're trying to erase for the sake of privacy.
However, you may be able to use a file recovery program like the ones listed here: https://www.lifewire.com/free-data-recovery-software-tools-2622893 (such as our own Recuva software) to attempt recover of these files.