What do you mean, "lost"?

Not very comforting:

Astronomers have lost track of nearly 900 asteroids that could be on a deadly collision course with Earth

"Between 2013 and 2016, 17,030 NEAs [Near-Earth Asteroids] were listed by the International Astronomical Union's Minor Planet Centre in Cambridge, Massachusetts. Of these, 11 per cent - nearly 1,900 - were labelled 'initially unconfirmed', meaning they were observed a few times but not enough to pin down their orbit."

We probably shouldn't be worried.  It's much more likely that lava will erupt in your back yard than a big asteroid will hit Earth and cause problems.

And of course, molten lava in your back yard is pretty rare.