Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Which parts are missing?
Is the flashlight new, or used/old?
new plastic tube
OK, then. Your Refun LED flashlight has been shipped incomplete. Return it to the vendor asking for either a refund or an exchange for another, similar or identical, flashlight in complete order and working condition. I hope it is not too late for a return-exchange arrangement with your vendor to still be in effect.
Contact your vendor or store first, about the matter of the missing part, though. They need to be informed, and perhaps to tell you how to ship it back and where, and issue an RMA or other identifying number.
If this answers your question, please rate my answer.