I lost count and had to start again.

我数着数着忘了，不得不又从头开始数。

《牛津词典》

The audience of several thousands—the organisers lost count at 7,000 in the middle of the five days—was mostly local.

几千名观众则大部分来自当地；在五天的盛会中，组织者在数到7,000名观众时却乱了阵脚。

youdao

He lost count of his grandchildren years ago, but believes that the brood could number well over 3, 000, and every individual counts.

几年前他忘记孙子的数目了，但是他相信把每个个体算上，数目绝对超过3000。

youdao

Howard Kramer says Elvis himself probably lost count of how many jumpsuits he actually owned.

VOA: standard.2010.01.07

He lost count and celebrated crossing the line with one lap still to go.

BBC: Simon unseats Smith in standings

I've lost count of how many retired numbers line Yankee Stadium's left field wall.

FORBES: Where It's All About The Game

On a 3-1 count, Hernandez lost control of an 88 mph changeup and the ball plunked off Rodriguez's hand.

WSJ: New York Yankees' Alex Rodriguez Breaks Hand