I can not open any documents, made in Libre Office.
I can not open Libre Office at all.
I cannot help. I cannot guess. I cannot explain.
Irony apart, if you expect any decent help, edit your question to tell at least your OS name, the LO version you downloaded and how you installed it.
Please do not use Add Answer but edit your original question to enhance the details of your question (answers are reserved for solutions to a problem on this Q&A site).
I am running Windows 10. The LO version is 7.1 and LO was on my HP computer used.