What's a good opposite of "keep track"? [closed]

Solution 1:

Actually, lose track of is quite a common phrase:

to lose contact with someone; to forget where something is. I lost track of all my friends from high school. Tom has lost track of his glasses again.

Solution 2:

Yes, you can say 'lose track'. It doesn't sound funny.

Solution 3:

"Lose track" is perfectly acceptable, in the sense of misplacing or losing contact information or forgetting what you meant to be doing, but in the sense of "something happened and [you] lost [a thought]", you might rather say you were distracted by other thoughts, or sidetracked by other activities.

A colloquial phrase for being lost track of is "dropping off the radar". [See my Update 1 comment]