Britney Spears' family secrets and sexy photoshoots have come to a very abrupt halt ... as the singer's Instagram account mysteriously disappeared off the site.

On Wednesday, Brit's IG disappeared without a trace, meaning she's losing her ability to speak out -- and show off -- like she normally does ... as you're aware, Britney used her social media to talk about family drama, the conservatorship, and love for fiancé Sam Asghari.

Confusion is moving fast among fans, with no answer yet as to why she's dropped off. Sam also has yet to comment publicly on her disappearing act.

A few weeks ago, Britney posted about her big return to Las Vegas -- as a tourist instead of a performer -- saying she loved being "treated as an equal" for once ...none of her recent posts foreshadowed a deletion.

While she used her platform to talk about the high points in her life, she's been known to use it as a weapon against those that hurt her ... making a lengthy post separate from her Vegas story, Britney went off at the entire entertainment industry, saying she was on the clock 7 days a week with little privacy.

She said, "I gave my all when I worked only to be literally thrown away … I was nothing more than a puppet to my family yet to the public I just performed on stage and did what I was told to do."

We have reached out to Instagram for comment ... so far, no word back.