openwebif for pli4

hi guys trying to install openwebif on my GENUINE vu+uno useing pli4 image when i inataal fresh pli4 image its there but after about a hour it gos mising when i go on plugin get message
some plugin are not avalilable
extensions/openwebif(no module name
extensions.openwebif._init_)
plzzz any help/info would be greatly appreciate

Any body please

thank you very much m8 i am technical dummy plzzzzzz can you be more specific, And explain step by step how to do it help/info would be greatly appreciate m8y